My account got banned for??Please justify.I do not know what is going on.

Today, 24/7/09
i was using my account (CrossRoadz)
to kill some Jr. Wraith for tablecloth.
Then suddenly, one of them dropped a white colored hat with the letter 'W' on it.
And i was: "Hey!thats the hat those maple admin npc wear!"
So i thought it was an even item so i picked it up and tried it on.
Then i saw the word 'GM' on top of the hat which my character was wearing.
So i was: OMG! this is a gm hat. Better take it off.
One second i was taking it off,
the next, i saw a pop up saying that i was blocked/banned.
Then the next second i found myself on the login screen, unable to log in.

Please Justify.
It might be my fault that i wore that hat,
but i did not know it was for GMs for i have not seen any GM wearing that hat.
And also, once i knew it was for GMs i immediately took it off.
And why did the mob drop something that a regular player shouldn't get their hands on?

Please Justify.