Sure does! Happens a lot to me. Here are some links to posts to remind you that you are in good company - the best really:

• Stupid mistakes I repeatedly make - thread started by brian_d_foy, author of one of the more popular Perl programming books.
• Avoiding silly programming mistakes - various practical tips on how to avoid unnecessary silly mistakes - including - "get a good nights sleep".
• And there are any number of nodes posted by senior monks solely to get a second set of eyes for the mistakes they can't see. To find them, try a google site search for "obvious mistake". I know of at least one of these that made it to the Best node of the day.

Posting questions, even ones that turn out to be silly mistakes can be very, very helpful to the next person down the road who makes the same silly mistake. Perl Monks is the great place it is because people have had the courage to make mistakes and let others see them.

Best, beth