Why was P mode using highest ISO possible?

----I posted this on question thread and it got buried with all the buying advice posts, so I am posting it here-----I have a Nikon D7000 and recently got a gig photographing nightclub photos. I usually hit the p mode when I need to get a critical photo. (with flash). lowest shutter limit is 1/80th. When I checked the photos from last night shot with P the ISO has been cracked up all the way to 6400, and f stop are higher around f11, f16. This is the first time it happened to me. Usually it keeps ISO down 800-2000 range when shooting P mode with sensible f stops. Anyone know why this happened? via /r/photography https://ift.tt/32b9XjW