I have had and solved this problem. It is due to humidity swelling the boards. For a while, I removed the stuck boards using a sail tie, in a loop, with a carabiner attached. I put the carabiner on the finger pull of the floor board and the sail tie around my hips and then by squatting and doing a quick leg press, popped the board out.
Finally, I used a hand plane and planed the edges down and then sealed them with epoxy and the boards no longer stick.
PSC31 #9 "Wayfarer"
The secret to sailing is good judgment. Good judgment comes from experience. Experience comes from bad judgment.