The OP's question was that he's getting charged, but the merc is suspended. That's a different situation, and it sounds like a bug.
I do have a question.... I have seen a situation recently where the merc won't zone with me. He still shows up in a group slot, but it's grayed out, like for group members who go LD or are in a different zone. If I look at the merc window when this happens, the button says "suspend", so the game thinks the merc is active. I have to suspend then wait 5 minutes to re-activate it, or camp and log back in.
If this was the case for the OP, then I can see the game charging you all night in the GL. The merc never goes to Passive mode, cause it's really not there.
If this is what happened to the OP, then suspend or log to fix it. If this isn't what happened to the OP, then it's a bug that should be reported.
Edited, Apr 7th 2013 4:37pm by tatankaseventh