As the title states, do chalices heal this quickly, or is it possibly tissue that had expanded over skeleton? I tried to take pics but my camera is junk. I believe it is a watermellon chalice.

usually doesnt happen that quick, but hey have seen weirder things happen.. maybe its just very healthy in your tank

It's not uncommon at all, thinner fleshed corals recover very quickly although they may not start growing new skeleton for a little while.

Well its not my imagination, when I purchased the frag and it fell off the mounting so I cut it in two. I placed each frag in the tank so I could watch where the cut was made. I did this more to see that there was no tissue recession and/or infection.

Each frag has an eye and the cut side of each frag has more than covered the exposed skeleton. Infact, it has continued to grow, rounding over and under the frag where it is glued to the disk.