Its easier for them to say "MCAT and GPA" than to elaborate on why you were truly rejected. In all likelihood, they probably though you were borderline for their school, and decided to give you a chance. But your interview didn't go well enough for them to give you a commitment. It doesn't mean that you had a bad interview per say, just that you had an uphill battle going in one way or another (be it geography, stats, etc.)
The important thing here is to introspectively reflect on your experience, and be better for your next interview. You can't dwell on losses. In medical school, you may do very poorly or even fail an exam - but if you want to be successful, you cant let yourself hang over that one poor performance. Learn and improve!
Good luck.