In 1.7.2 you added the feature of punching ItemFrames to get the item back from them, however, I am not sure if it was intentional or not, other damage sources, such as have an anvil fall into the same blockspace as it, explosions, fireballs, and arrows, also now cause it to drop the item without breaking. It just didn't seem correct that itemframes with items survive explosions and those other issues.