I pressed mine back on and it's not showing any signs of coming back lose.

I don't think they pressed it on at the factory. Guy who puts headliner in probably just lays it in there and someone else probably checks to make sure headliner is popped in and is supposed to press on gasket.

My guess is there's one guy at the factory who probably let the 1st 500 cars off the line without pressing the gasket on.

When Infiniti realizes this, they will probably find this guy, tell him that he has single handedly disgraced the company in front of 1000 of his co-workers, then hand him a short sword