My hatchett became heated and loose, as it was left sitting too close to the fire overnight. The handle is some type of wood composite, with a rubber grip. I think it can be saved, but it needs to be safe as well. Also, the blade was heated, but not warped, do I need to harden it again to keep an edge, even if it was never "red hot"?
Wood shrinks when dried. Attach the head loosely and soak the head and handle in water a day or two (if completely immersed, the head should not rust noticeably). Unless the hatchet was hot enough to burn the handle, the blade should be OK.
If there is no wedge, you'll need to add one for safety, see here.