Am I being extra?

Does he usually open mail? My husband never opens the mail so that would be confusing to me. I think it could be an honest mistake I don't think I would think too much of it if he usually reads the mail.

He does not and he knew I was waiting on this letter.

That seems…. slightly malicious to me. If he knew you were waiting on it, why didn’t he bring directly to you?
Why put it UNDER something and not tell you about it at the very least, since he decided to take it upon himself to open the mail suddenly, now that you were waiting for something.
Maybe I’m reading too far into it. But that would frustrate me too, would make me feel like he was 1 trying to hide it 2 doesn’t want me to do it

I'd assume it's by mistake and watch him. Chances are he may not be as happy because you'll be doing something for yourself. It's just life. But may not be the case here. He was snooping to see if you got it smdh then didn't directly inform you about it ....yeah.. watch him.

That man doesn’t support your plans girl so keep him away from it. Do not trust him during your self empowerment journey because that’s the first physical sign of resentment.
The fact that he isn’t happy for you to elevate in life is a huge red flag and so icky. It’s giving insecure and selfish.