Destroying grass lead to wooden door spawn

Was walking along destroying grass when a wooden door was dropped (in the same way that seeds would be) - Could be a mistake on my part but I never had a door in that area or in my inventory beforehand. I am 95% sure that the door was spawned when I destroyed the grass. This has only happened once and I have not seen it since. This issue occurred in a single player world with cheats enabled, normal world generation with structures on. I have not been able to replicate this and it is the only time that it has ever happened to me. As such I don't know if logging in and out has fixed this, or if closing the program fixed it.