It's happy! Miniature roses are only smaller in bloom and leaf size. The plants themselves can be as large as a floribunda rose. And there are climbing minis that can get 12 feet tall! There is probably nothing at all wrong with your mini except that it's starting to mature and grow larger.

Thank you for responding. I was thinking I needed to cut it back or something. That maybe it was the root stock putting up a branch. I'll look forward to seeing the buds open on the larger branch.

Minis are typically not grafted. I'm with seil, sounds like a happy plant. BTW, of my minis get to 4' tall.

Thank you so much for responding. It didn't produce flowers last year but i hope it will this year.