Carbon monoxide detector going off

Last night in our motorhome the carbon monoxide detect kept going off. I opened all the windows and vents and kept hitting reset but after a few minutes it would go off again. This went on for about 30-40 minutes. I finally dismounted the detector and held it up to an open window. Just as I was about to start cutting wires to shut it down, the red light went out and it quit beeping. I am trying to figure out what caused this. We are parked on a lake with other RVers. I did have a fire going outside before the alarm went off. I got up and closed the door (just had the screen door closed) at one point because I was starting to smell the camp fire a bit inside. Could this have caused the detector to go off? I have had issues with the propane detector going off in the past when the wife put on perfume but I have never had the issue with the carbon monoxide detector.

Burch