I don't know about contacting admissions, but I got a secondary and I'm not "super competitive" in terms of MCAT and GPA, so that's def not the reason why you didn't get one.
A few people have said they screen manually, so if that's the case, there is going to be a lot of variance in when people here back. I've worked in a office (not med school) where candidates were screened manually and they literally give a bunch a people a pile of applications and some staff get through their pile faster than others.