Is it my 12v battery?

You can check the 12 volt with a digital multimeter. There's a chart here (about 2/3 down the page) on what the readings mean:

The 12volt Side of Life (Part 1)

 

I just checked voltage on a new battery I put in our son's car last weekend, and it was tipping between 12.64~12.65. I guess what I'm saying is your number sounds good

 

When that happened to me it was my dog, he had stepped on the P button and put the car in neutral.

 

This test is most meaningful if the car has been turned off overnight, or at least for a few hours, and not yet turned back on to 'Ready'. If you repeat it first thing tomorrow morning, I suspect the voltage will be lower, but still good.

This, or accidentally trying shifting the car into Reverse, should cause a double beep warning as it goes to a fail-safe Neutral. Intentionally going into Neutral requires holding the shifter in N for over a second, and won't give an audio notice.