No problem! That is exactly why we're here =)

One thing to consider when doing stat is that it operates off of the current working directory. Perhaps $_ isn't really pointing to a valid file? Proper error checking is very good practice and often needs very little extra modification:

die "Bigger problem: '$_' doesn't exist!" if not -e $_ ;
if ( time - (stat $_)[9] > 1200 ) {
   print "ERROR MESSAGE"
}
[download]

Oh, and no, stat works just fine by its lonesome. No prep is needed.

-Ducky