Ive carried every phone in my pocket, even my storm 1. I'm a professional firefighter in a good sized city so I really test the phones in silly environments. Wherever I go they go. I had never had an issue with dust under the glass on any phones until my 1st droid. It started accumulating from the 1st week and just got progressively worse. I saw a bunch of posts on this and various other forums but none had a solution. I called up vzw directly, the rep looked around on his end and couldnt see a solution or even find any similiar issues. I pointed him in the direction of this and other droid forums. He posted a report to Motorola and sent me out a new unit.
I've had my new unit for over 2 weeks, and it still goes into my pocket, but this one has zero dust under the glass.
TLDL: If you have this issue dont 'just deal with it' or go to a VZW store, call them directly. I think its 611 from your phone. Tell them what the issue is and they'll notify Moto of the problem and send you a new one.