There’s a Chipmunk in my Lens!

For Christmas, I received two new lenses among a few other techie things (more to come about that).  One of the lenses, a Tamron 17-50mm F/2.8 snazzy number, makes a strange chirping noise whenever it autofocuses. The pictures turn out fine, but that noise does get very annoying–sounding eerily similar to a chipmunk.  There is only one thing that worries me about this noise.  The whole point in this lens is for low-light photography (hence the low aperture).  The situation in which I would need this most is in stage photography, a place where you need to be as quiet as possible.  What do we think?  Is it a problem with the model or a problem with my particular lens?  I guess I’m not going to worry too much.

CHIPMUNK!!!