Rogue PickPocket question

[Merekai]

Hey all I had a quick question about my rogue and his pick pocket skill. I was in Cazic Thule the other day farming some ravenscale and when we were fighting one of the named I was actually able to steal the Lizardscale Cloak off of the Templar who drops the leggings as his rare drop. His body had no loot on it, since I had stolen it during the fight. Just wondering if this was something that is super super rare, or something that is a bug and not supposed to happen? Needless to say my group mates were not so thrilled to find out I could do that!

Would appreciate any responses from people with similar experiences. Thanks!