If he is a senior it’s reasonable for him to stay out past 12 occasionally.
He did the right thing, he came home and asked to go out more instead of missing curfew or calling for an extension.
You should be more flexible
Moody won't always be about you and your rules. There may have been some teen drama that needed fixing. It isn't always just mindless partying (socializing). It's relationship. Probably fragile relationships since Senior year wraps up and these young people are facing the biggest transition of their lives. They are breaking away from each other. Just something to keep in mind. Your rules may become less important than doing the right thing (for them the right thing may be needing to be there for a friend)