This was a truly minor controversy, but Romney needs to show better political skills. It was slightly inept to let himself be photographed near the sign and quite stupid to hold up the sign, but once it happened, he should have had an elegant explanation. With all the characters running around to campaign events trying to lure the candidate into a "macaca moment," how is it Romney wasn't ready for this guy?
ADDED: The second link was wrong for a few seconds. If anyone saw it, they would have found this post waaaaay more amusing than it is!