Should I get paid for a tiny amount of over time?

At my job we aren’t supposed to work over time. On an ending pay period day, Friday, I was about to leave but my boss had an issue. He was waiting for someone to pick up a key but he had to leave. I volunteered to stay an extra 15 minutes past my hour.

He said ok and well the person never showed up. Anyways i noticed that my time was over and I told my supervisor and asked if I could “flex” my time which we usually can. She said “it’s ok if you’re over 15 min” but then I noticed I wasn’t compensated for that 15 min.

Should I even bring it up to get paid a few bucks?? If I didn’t work 15 minutes they wouldn’t pay me so that wouldn’t be fair if I didn’t get paid the extra few dollars right?