Battery Dying, but okay????

[Egan]

I bought my H2 used in June of 2012 and it had a brand new battery in it. In August of 2012 I had the stereo going while parked at our campsite. The key was moved forward to "run" and within 30 minutes the battery was dead. I got a jump and when we got back to civilization I went to the local AutoZone to buy a new battery. The guy tested mine and said there was nothing wrong.

Flash forward to last week. While at the gas station filling up I left the key in "run" so my bluetooth wouldn't disconnect. I pumped gas for maybe 10 minutes (24 gallons or so) and when I went to start the truck, it wouldn't turn over (still had accessories though). She started on the first try while being jumped by a Tacoma.

I was about to go buy another battery, but this just seems weird. The truck starts just fine every morning. She sat for 7 days while we were on vacation and started right back up - so why does it only take 10 minutes to kill the battery with the engine off?

Any ideas?