Mine does that also but i have the 4 case not the 4s case. From hwat I have heard this is the differance and if you call otterbox they will replace it if you bought the 4s case not the 4 case.
I am new to this forum. I have questions but will serch first to see if i can find the answers. I am not new to iphones just new to this Forum. I have had the 3gs, 4, and now the 4s.