Should I have stood for the national anthem?

I'm at the kids' football practice and some of the other teams have games today. Before games, they go on the intercom to say a prayer and the national anthem.

For practice, I always just sit in my car to watch them. So I'm sitting in my car when the national anthem starts. Everyone else is standing around, and I'm sitting in my car. I thought about getting out, but I felt like that may have been a bit much, but at the same time, I feel disrespectful.

The kids have never had a practice on the same day as a other teams have games, so I have never dealt with this before.

Thoughts? Should I have gotten out of my car? So I know what is and isn't acceptable for next time this happens.