Drexel receives well over 10,000 apps and they interview 1,300. There's more to the decision process than GPA & MCAT. Every personal statement gets read, and the higher-ups in the admissions process at Drexel have said openly that it can make or break your chances of getting an interview. Also to be considered is that a lot of the process is arbitrary, who knows what little things may catch someones eye on one app but not on the next. The majority of applicants are going to have competitive stats, shadowing, research, and volunteer experience. Considering that so many people have those on their resume, I imagine it's quite a snooze to see over and over. Basically, I'm not so sure you're not getting an invite because they think you're using them as a "safety", though I wouldn't be surprised if there is some arbitrary cut-off in the head of some of the reviewers, but I highly doubt that a mid-30s score would be a cut-off. Ultimately, don't flatter yourself with thinking that they think you're too good. It could very well be that they think you actually aren't good enough.
[Oh, india45, I'm not necessarily replying to you specifically.]