Belt Tensioner Bounce at Idle Normal?

I’ve replaced the serpentine belt on a 06 Pontiac G6 (6cyl) and I noticed at idle the tensioner has a slight bounce to it… Is that normal? It goes away when you hit the gas. Apparently the tensioner was replaced less than a year ago

I attached a short video. HTTPS://

Yup, that’s normal.

It sounds like it is doing its job. All that bouncing they do is why they wear out and have to be replaced once in a while.