I think that's an irrational fear that everyone has a bit, when i got my AS grades this time I got them online and was convinced it had been some sort of error (they were better than i anticipated). I went in to college to get the official print outs and was convinced even as I opened the envelope that they were wrong, but they were completely accurate. In other words, that kind of stuff doesn't happen, so chill your beans and be happy cuz u did awesome.