diff --git a/consensus/src/quorum_store/batch_store.rs b/consensus/src/quorum_store/batch_store.rs
index 3cd381fcf8fc9e..827c576e535dde 100644
--- a/consensus/src/quorum_store/batch_store.rs
+++ b/consensus/src/quorum_store/batch_store.rs
@@ -12,10 +12,7 @@ use crate::{
     },
 };
 use anyhow::bail;
-use aptos_consensus_types::{
-    common::Round,
-    proof_of_store::{ProofOfStore, SignedBatchInfo},
-};
+use aptos_consensus_types::proof_of_store::{ProofOfStore, SignedBatchInfo};
 use aptos_crypto::HashValue;
 use aptos_executor_types::Error;
 use aptos_logger::prelude::*;
@@ -30,9 +27,12 @@ use dashmap::{
 use fail::fail_point;
 use once_cell::sync::OnceCell;
 use serde::{Deserialize, Serialize};
-use std::sync::{
-    atomic::{AtomicU64, Ordering},
-    Arc, Mutex,
+use std::{
+    sync::{
+        atomic::{AtomicU64, Ordering},
+        Arc, Mutex,
+    },
+    time::Duration,
 };
 use tokio::sync::oneshot;
 
@@ -262,9 +262,13 @@ impl<T: QuorumStoreSender + Clone + Send + Sync + 'static> BatchStore<T> {
                 // Skip caching and storing value to the db
                 Ok(false)
             });
+            counters::GAP_BETWEEN_BATCH_EXPIRATION_AND_CURRENT_TIME_WHEN_SAVE.observe(
+                Duration::from_micros(value.expiration() - last_certified_time).as_secs_f64(),
+            );
 
             return self.insert_to_cache(digest, value);
         }
+        counters::NUM_BATCH_EXPIRED_WHEN_SAVE.inc();
         bail!(
             "Incorrect expiration {} in epoch {}, last committed timestamp {}",
             value.expiration(),
@@ -320,12 +324,6 @@ impl<T: QuorumStoreSender + Clone + Send + Sync + 'static> BatchStore<T> {
         }
     }
 
-    // TODO: make sure state-sync also sends the message, or execution cleans.
-    // When self.expiry_grace_rounds == 0, certified time contains a round for
-    // which execution result has been certified by a quorum, and as such, the
-    // batches with expiration in this round can be cleaned up. The parameter
-    // expiry grace rounds just keeps the batches around for a little longer
-    // for lagging nodes to be able to catch up (without state-sync).
     pub async fn update_certified_timestamp(&self, certified_time: u64) {
         trace!("QS: batch reader updating time {:?}", certified_time);
         let prev_time = self
@@ -346,7 +344,7 @@ impl<T: QuorumStoreSender + Clone + Send + Sync + 'static> BatchStore<T> {
         }
     }
 
-    fn last_certified_time(&self) -> Round {
+    fn last_certified_time(&self) -> u64 {
         self.last_certified_time.load(Ordering::Relaxed)
     }
 
diff --git a/consensus/src/quorum_store/counters.rs b/consensus/src/quorum_store/counters.rs
index 82cb2ac8457516..fc5554df5e99e8 100644
--- a/consensus/src/quorum_store/counters.rs
+++ b/consensus/src/quorum_store/counters.rs
@@ -130,6 +130,25 @@ pub static EXPIRED_PROOFS_WHEN_PULL: Lazy<Histogram> = Lazy::new(|| {
     .unwrap()
 });
 
+pub static GAP_BETWEEN_BATCH_EXPIRATION_AND_CURRENT_TIME_WHEN_SAVE: Lazy<Histogram> = Lazy::new(
+    || {
+        register_histogram!(
+        "quorum_store_gap_batch_expiration_and_current_time_when_save",
+        "Histogram for the gaps between expiration round and the current round when saving proofs, and expiration time is lower.",
+        // exponential_buckets(/*start=*/ 100.0, /*factor=*/ 1.1, /*count=*/ 100).unwrap(),
+    )
+    .unwrap()
+    },
+);
+
+pub static NUM_BATCH_EXPIRED_WHEN_SAVE: Lazy<IntCounter> = Lazy::new(|| {
+    register_int_counter!(
+        "quorum_store_num_batch_expired_when_save",
+        "Number of batches that were already expired when save is called"
+    )
+    .unwrap()
+});
+
 /// Histogram for the gaps between expiration round and the current round when pulling the proofs, and expiration round is lower.
 pub static GAP_BETWEEN_BATCH_EXPIRATION_AND_CURRENT_TIME_WHEN_PULL_PROOFS: Lazy<Histogram> =
     Lazy::new(|| {
diff --git a/consensus/src/state_computer.rs b/consensus/src/state_computer.rs
index 75f93ec646919f..61dcf39c47fd1d 100644
--- a/consensus/src/state_computer.rs
+++ b/consensus/src/state_computer.rs
@@ -54,7 +54,7 @@ pub struct ExecutionProxy {
     state_sync_notifier: Arc<dyn ConsensusNotificationSender>,
     async_state_sync_notifier: aptos_channels::Sender<NotificationType>,
     validators: Mutex<Vec<AccountAddress>>,
-    write_mutex: AsyncMutex<LogicalTime>, // TODO: mutex needed?
+    write_mutex: AsyncMutex<LogicalTime>,
     payload_manager: Mutex<Option<Arc<PayloadManager>>>,
     transaction_shuffler: Mutex<Option<Arc<dyn TransactionShuffler>>>,
 }