Azalea leaf gall. Not uncommon and a few disfigured leaves can just be handpicked. Don't compost or drop them on the ground, dispose of them.

I just pulled a few off an established azalea hedge here yesterday. We've been here two years, I didn't notice any last year. If in future springs it appears the infection is becoming much worse, I'll consider a fungicide.

https://ag.tennessee.edu/EPP/Extension%20Publications/Plant%20Diseases%20Azalea%20Leaf%20and%20Flower%20Gall.pdf

While not important for the gall, your approx. location could be important with other questions. A bit of sleuthing led me to someone else asking where you are in wanting to respond to your tree question. My Houzz, Edit Profile, Advanced Settings, Climate Zone, then click Update to set your preference will add your Zone, State to your user name line so we know....Thanks!

zone 6

and by the way thanks for the info. should I burn the gall?

If you keep a burn pile, that would probably work. Otherwise I'd put them in the garbage, not the compost.