Yeah, as it warmed, CO2 came out of solution and pushed the hydro up. It probably is at 1.039, which means it is fermenting, although a little slow - expected from the underpitch. Let it warm like you're doing, and check it in a few days.
Looks like the gravity is down to about 1.028/1.029. Need about 4 more points before going with a d-rest. It will get there. The under-pitching is just slowing things down.