Answering why questions

Zavier is getting better at answering "why" questions and talking about feelings. We had this conversation the other day:

Zavier: (giggling in the bathroom)
Me: Zavier, how do you feel?
Zavier: I feel happy
Me: Why are you happy?
Zavier: Because I peed on potty
Me: Good job, I'm proud of you. I'm happy too.

And this one today:

Zavier: (angrily clenching his fists at the gate)
Me: Zavier, how do you feel?
Zavier: I feel happy
Me: You don't look happy. Try again, how do you feel?
Zavier: I feel mad.
Me: You look mad. Why are you mad?
Zavier: (no answer)
Me: Try again, Zavier. Why are you mad?
Zavier: Because I want computer.
Me: Well you can't have the computer until you go potty.
Zavier: (sighs)
Me: Go potty please.
Zavier: (runs off to use potty)