On Fri, 11 Sep 2015 09:36:48 -0700 (PDT), trader_4
wrote:

If I cut slits between the sub floor boards with a circular saw, would
that allow the floor to expand without bulging? Or should I just remove
the screws and live with squeaks?

They probably didn't leave the required gaps between sheets
to allow for expansion. Still seems unusual that just screwing
it down more would cause this. I'd certainly try doing a relief
cut, you would think that would work, if that's the source of
the problem.

In my former house, adding a sub floor, used T&G 3/4" ply with liquid
nails (joist) before the floor was nailed down. Solid.

Without that, a good sub floor _would_ have a ~3/16 - 1/8" gap between
plywood sheets at the end joints.