Munged sample sizes not equal to input

[rrydbirk]

For munging, I ran this:
python ldsc/mtag_munge.py
--sumstats Nalls2019/nallsEtAl2019_clean.tsv
--a1 A1
--a2 A2
--merge-alleles data/ldsc/w_hm3.snplist
--keep-pval
--p p
--out Nalls2019/Nalls2019

Following munging, I get "weird" N (sample sizes). As an example, SNP rs6678176 has N "378755.399715", but my input summary statistics file looks like this before munging (from nallsEtAl2019_clean.tsv):

SNP A1 A2 freq b se p N_cases N_controls N_total
rs6678176 T C 0.290 0.0322 0.0245 0.188 26421 442271 468692

I'm curious why these Ns are so different. Is this something I should worry about?