Is there sufficient log activity for the $hrmin check to have a large enough resolution, or is it possibly skipping over your check time?

If the check is only for the date, why not do a comparison to see if the last date matches the current date?

I also note that you are never recalculating the datetime, so $hrmin and $ymd never change during the lifetime of your while (<$sock>) loop.

Update: Be careful if this restarts. Instead of appending to the current date's log file, you will clobber it and truncate it at the beginning with your open statement. Consider using '>>' instead of '>'.