Random electrical issues

The other day I set my car alarm while I was in the car, forgot about it, and started the engine which set off the alarm. While the alarm was going off, I noticed that for whatever reason it made the battery light come on. I turned off the car, started it back up, and the battery light was gone.

However, now the battery light will stay on for a few seconds then disappear but only when I first start the car. So, if I'm driving to the store it will come on when I first start it but when I'm driving back home the light is nowhere to be found.

Does anyone have any idea what could be causing this? This light was not on prior to me accidentally setting the alarm off. The last time the battery light did this was when a dealer screwed up on my oil change and I ended up with a new battery 2 weeks later. That incident was about a month ago so I know it's not the battery.

I have about 139,000 miles and locked the doors.

If you're in America and if you don't have the tools and skills to do this (or if you're just lazy like me), take the car to Autozone and they will check the battery/alternator/starter with their system and tell you what is wrong. Of course they'll try to sell you something but the diagnosis is free unlike a shop.