wrong advice, don't listen to me. nothing to see here, move along folks.
You need to escape the '-' character, because it's interpreted as a range.
update: that was a little short, try this:
$TEMP1 =~ /^(A\-[0-9]+\-[0-9]+)\-AM/
notice the '\' characters. And the '^' so it'll only match files beginning with "A-123-123-AM"
update numero deux: woops, guess i was wrong. need to get handle on rexeps, sorry. (and actually read posts)