I spawned a new world in Survival to test out the new biomes and features, however I noted that a lake near my location had grass on gravel for a split second. The gravel fell like normal and the grass disappeared.
I also noticed that there was floating grass near the gravel. I could easily break the grass, though this was unrealistic and should be reported.

I know that there was many other reports on this same thing happening, though these were for different versions and apparently were all resolved. Hopefully the Mojang crew can fix this issue.
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I was expecting that grass would not be on the gravel or floating in mid-air. I mean, that is how Minecraft worlds work.
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Grass was partly on the gravel near the lake and disappeared upon the gravel falling. What I noticed most of all was that there was grass just floating in mid-air.
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1. Run Minecraft 1.7.2.

2. Create a new world using the seed -1832090069312539477. Choose the default world type. Generate Structures: On. Run the world in Survival.

3. You should see a lake near your location. Gravel will fall, signaling the location of the floating grass.

4. Floating grass, and if you look immediately, grass on gravel.

-Collectics