A number of U.S. iPhone users are complaining of recurring mystery data usage appearing on their AT&T accounts. According to an Apple Support discussions thread, the mystery charges appear to be occurring late at night, typically between 1:00 and 3:00 a.m. Some users report that these late night data sessions have reached as high as 70MB, theoretically ruling out the possibility of simple statistics uploading, as one user points out. None of the users reporting problems has yet been able to identify the culprit, and neither AT&T nor Apple has been able to offer any explanation.