Why Wasn't I Invited?

Nothing bugs Pee-wee's flowers more than having a caterpillar in their flower box until Magic Screen shows how a caterpillar can turn itself into a beautiful butterfly. The caterpillar's not the only uninvited creature around when Cowntess has a birthday party and invites practically "all" of Puppetland except Pee-wee! Is she mad at him or just being moody?