checking .htpasswd files on paysites

AttentionPaysite owners:
I just had a client who checked his and found that there was a small problem with the epoch password script, so it was still lettting in members that had expired a few months ago. Epoch upgraded the script very quickly (nice service on their part) but he wouldn't have noticed this without having done a check on his password file.

So, do you comb through your password files to ensure all entries are valid? And if so, how often?

cheers,
Luke