In preparation for a pending (~7/21) addition to the family, I've gone ahead and mounted a rear facing infant child seat in the center rear of my 2005 4Runner (non-LATCH). My question is to those of you with these Graco infant seats that snap in and out of base units: I've mounted the base unit in, cinched it down, had it inspected by the local fire station with no issues, but over the course of the last few days, it seems that the tension in the shoulder belt has caused the base to no longer sit level (it's currently just the base, not the whole seat). It's riding up on the passenger side. Anyone else seen this issue - should I be worried about this, or will it go away with the extra weight of the seat to hold it in place?