I was asked by the chair of the program where I also did my undergrad why my college grades were so mediocre. It was tough to swallow that question given my college's notorious deflation and the chair's college's notorious inflation, but I kept my cool. Talk about maturity, learning how to learn, in my case taking on too high of a course load, etc. If all else fails just point out your honors and high step scores, and hope the interviewer moves on. That's what I did. Still put me off the program a bit to be honest, and I ranked it lower (other reasons as well). That was the only person of 15 interviews that asked.