Yep, that's kinda what I was thinking (and hoping). I hope it's just too much pre-load. Mis-alignment could also be an issue, but I would think heat wouldn't affect this as much. They should expand at roughly the same rate, and therefore not become MORE out of alignment? Also, based on how much force it took to pop them out, I'm guessing that everything is just way too tight.

I have a bore indicator, so I can get centered over the hole and open it up a bit. How do I go about calculating pre-load? These bearings are just to stabilize the top portion of the spindle and really don't do much else, so could the pre-load be a bit less? For example, could they just be a simple press-fit and still function well?