Leaf and Log Decay

Hey

So I was trying to make a tree house using worldedit.
(I have done this at least 5-10 times with no problem)

I made the tree and everything, I cleared space for rooms, then I went to add stairs around the trunk, and I see logs and leaves and apples falling, at first I though it was a creeper that blew up behind me, but then I looked up and saw logs and leaves falling, there were LOADS.

So I quickly made a region with WorldGuard and WorldEdit, and when my leaves decay, I just do /region flag [name] leaf-decay deny, and it works, but it didn't this time!

Please, if any of you have any answers to why this happens, please could you help me?

Here are some photos of what it looks like...

http://gyazo.com/23b4a15dcb98fd1119df30e750d44858

http://gyazo.com/e4a3fecc8a2f64550e7fc65cbed31454