Players get creative on join

This has been happening for a few weeks. Its not regular in any sort of way, but my members sometimes get creative when they join. For some reason i haven't been able to recreate it an anyway. But i have done /whois, and they are in fact in creative. They didn't have it when they left, and they don't have the perm to switch it. What gets me is it irregularity.

These are my plugins:
Orebfuscator
MultiInv
WorldEdit
TAGAPI
SimpleAutoAnnouncer
Battlenight
Vault
Standardbooks
Pex
Wither
NoobResponse
DwarfForge
WorldGuard
ProtectionStones
ChestRestock
Craftipedia
Survivalgames
Coreprotect
EndlessEnchant
BKCommonLib
Myworlds
Lockette
Simplespleef Evolution
Rounds
ManySmallTweaks
Essentials
CreeperHeal
ServerSigns
VanishNoPacket
ChestShop

If you have any suggestions about why this may be happening, it would be appreciated. I'm running bukkit version 1.4.2R0.2

 

In server.properties
do this:
gamemode: 1
But that makes it creative forever.
If that doesn't work, try and configure myworlds.

 

Is there a creative world?

 

show properties file