Every now and then their will be a bug or 2 and one of them is that and sand and stuff and one that i got that i litteraly Thanked the Heavens i didnt die was that i had 32 diamonds and i dug my last one....( mistake 1 dug under myself) and when i got the last diamond lava started to come towards me and me being the lucky i had some fire resistant armor on and i was able to survive and my face was like

I got it in 1.8

I got this today in 1.1 :/.

Its the same thing as when sand and gravel spawn floating, it has something to do with chunk spawning I believe, some chunks have floating blocks on occasion due to a bug in the code or something.

I got it in 1.0 and 1.1