Kheapathic

I was heading home today and on reaching a stop sign my car started beeping (not a soft seat belt beep, but a piercing beep). I pulled over, turned my car off, let it sit then started it back up and nothing came up. I reached another stop and when the auto-stop engaged it started beeping again. I let it run and after about 10-15 seconds it stopped. Reaching yet another stop sign the same thing happened only this time it stayed on until I reached my parking spot (about 3 minutes). I wasn't sure what was wrong, nothing comes up on the code reader and after driving it around and watching my instruments I can honestly say it only happens when my auto-stop engages. Anyone have any idea what might be causing it?