Looks like Red Octane is is indeed putting out a "recall" on specific models of the Xbox 360 version of the Guitar Hero II controller for the bum whammy bar. Kotaku posted an official response from a customer service rep.

"We have isolated this issue to two model numbers that can be found on the guitar's packaging. The numbers are 95065 and 95055. We are asking that customers who purchased their items from a retailer perform an exchange with that respective store (for a model number other than the defective two listed above). Customer's who purchased through our online story can complete an rma request for their defective item and we will exchange it for a fully function guitar controller. We do apologize for the inconvenience and will

For those unaware of the issue, the bad models have Whammy Bars that do not stay in position, but tend to sag down and point toward the ground. A real pain-in-the-you-know-what when you have to hold the bar in your hand while trying to play the game.