This is only a comment:
I suppose that you don't have any control at all over the format of this file. However, Tux, I and many other Monks would counsel you to use a YYYY-MM-DD format with leading zero's required in case of single digits (if you have a choice). This format winds up being "ASCII sortable" and that is a huge advantage with Perl. I personally generate all log files in UTC but I am often looking at international network files. Mileage varies with choice of time zone.