Anyone ever experienced a vibration noise coming from what appears to be the foam surround on a woofer? While it is only noticeable at about 6" from the woofer, I'm curious if this warrants concern as this could be signs of a problem occuring. It is only heard at frequencies of less than 140hz and the buzzing mimicks the frequency. If i lightly place my finger on the edge of the surround I can make the buzz dissappear or dimish greatly. I've already contacted the manufacturer but I was wondering if any of your have seen this issue before.