In case you though AT&T wanting to run a credit check before they sell you a prepaid phone was as dumb as AT&T could get, reader Dan writes in to tell us about an AT&T store that wouldn’t sell him a phone because he was already an AT&T customer. If he hadn’t copped to being an AT&T customer, he could have walked out of the store with a lovely LG CG180 Go Phone. But since he admitted he had an AT&T number, the sales reps at the store wanted him to put an extra $100 down. More, after the jump.