Chevy Impala "battery saver active" in aux mode.

Hi.
I own a 2012 Chevrolet Impala LTZ. While I was on break at
work, I went out into my car to listen to the radio. I put it in
aux mode. After about 20 minutes, my break was almost
over, so I went to shut my car off. I noticed on the DIC the
display "battery saver active" was lit up. I turned my car off
and turned it back on. The engine turned over fine and there
were no issues starting it up. The message that was there
was gone. While I was sitting in the car with the radio on, I
was also charging my electronic cigarette with a car
charger. It had been charging in my car for a couple hours,
and I had two breaks before where I was out in my car
using aux mode. I unplugged my electronic cigarette after I
saw the message. My radio was working fine, and I didn't
notice any issues with my ac/fan (I had it on low though).

I just replaced my battery and had all the wiring checked
three months ago. Everything was fine. My car has over
110k miles on it. I'm just curious as to what might have
caused this and if it's a big issue. Could it have just been a
computer glitch? I'll update this after work if I have
anymore problems.