Fliying frames

I was making a huge map of my old world, when I
hit new generations I made map of them because I
didn't notice that it's new generation. When I came back
to map, I destroyed wood behind a frame. I should fall
down, but it didn't.
Frame was floating few seconds, then it
dropped, as it allways did.

Steps to Reproduce:
1. Place a block
2. Place a frame on that block
3. Then break this block behind a frame.
4. Done, floating frame is placed! (but suddenly BOOM,
It became an item)