Unusual call drop problem

Hi all,

I have a problem with my iPhone 4 dropping calls.the problem is that I can be mid way through a call when it drops out. Either the person at the other end goes quiet or I go quiet to them and I have to end the call. The call does not just hang itself up. When this happens I have had a look at the bars on the display to find that they're full. Also I hold the phone on my right hand and make sure not to cover the area affected by the death grip.

This is a major issue for me. Does any one else have this issue before I return it to Apple for a replacement?

 

I'm not asking IF I should return it. I'm asking if anyone else has this issue as there may be a simple fix that I've missed in the mass of threads on here that means I don't need to return it.