Agree with John that there is a big difference in fit with temperature,
and you are seeing extremes. My 28 canopy was binding and hard to open
after baking on the ground in the Arizona sun. I relieved it just just
enough to stop binding but after cold soaking at 9k on a winter flight
there is a large gap front and rear. It also seems to fit high when
cold but flush when warm.

I'd suggest you don't change anything unless the problem is there both
hot and cold.

(temp ranges in Arizona +115 F on ground in summer to well below
freezing at altitude in winter).

Andy