I WASN'T PLAYING ON SURVIVAL, IT WAS ADVENTURE MODE

So I was just playing on adventure mode in 1.4.2 where you can now mine and place blocks, and say that there was a tree. I was just "mining" the wood with my axe (I just clicked on it but I didn't let it break), and I switched to my pick (or any tool or item or block) and I tried to mine it and it did actually start mining the wood even though I was using my pick. The wood did not break, but when it was about to, it just "restarted" and went back to where it was starting to break. It only happened on the last block that I started to mine like if I was mining sand with a shovel, then I could "mine" only that sand block until I started to mine another sand block with my shovel. The speed when mining the block with the unproper tool is the same speed like if you were mining it with your bare hands. So yeah, I just noticed this, and I just wanted to let you know.

Thanks,
Bill Stevens