You most likely have Reliable calipers which have a known issue for hanging. I'm thinking that this may have caused the heat issue and seal problem. There was a recall on them some time ago that has most likely expired by now. Reliable is now out of business so you'll need to replace all four calipers most likely on your own. The replacements sent to me from Reliable were Kodiac. I'm sure others would work but these were direct replacements that worked with the existing brackets and rotors.
I say replace all four as if one is hanging now the others are most likely soon to follow and overheating a rotor will lead to bearing failure. Better to get them all now before the repairs start adding up.
It's also possible that you have the plastic cap version of the outer seal, the cap cracked or seal failed for whatever reason, the oil ran out and then the bearing heated up from no lubrication.
Either way I' be looking real close at those calipers with their track record.