Hi - My wife and I just signed up with AT&T last night and bought two 3GS. One thing she noticed is our screens are a little different. Mine have a little more yellow and hers appears to be more blue. From reading forums today, it appears the yellow screen is just a variation of the LCD. My wife just so happens to like my slight yellow screen a little more. The display color doesn't matter to me. In fact, I'll can't even really tell much difference. Is it okay if we simply swap phones and of course swap SIM cards so we have our correct phone numbers? I wasn't sure if that was an issue with AT&T or Apple by doing that since we just signed up yesterday. Thanks.