Does your 9650 battery door stay in place when your move it just a little bit left and right? I might just be obsessive but I dont know If this was the case when I first got the phone and its driving me mad.
Mine is solid as a rock, but then, so was my Tour...
If it bothers you enought, put a small piece of electrical tape where the door clip attaches. That should snug it up, I heard some of the Tour folks that had the loose doors did that and it fixed the problem. If everything else is solid with your device I wouldn't recommend swapping it.
mine was solid for 3-4 days than started getting wiggly. I put a piece of tape where the door clicks in and its perfect now.
just to throw it out there, Evo4g guys had problems with the door not being flush along the sides, so they put post-it notes folded up dead center on the battery to make it flush.
you'd think companies could get something so simple right.