I’ve been getting cracking and popping in my knees and ankles since I started mobility work about 2 months ago. Still hasn’t stopped, but I also keep gaining ROM.

As for the sore muscles, I definitely feel sore and tight in my hips and groin. Even if I don’t workout for 2-3 days (I still do mobility work), my hips still feel pretty tight and every morning I feel like I have to work my corners. First thing I do every morning when I get to work is put a foot up on my chair, drop down into a semi lunge position, load my hip, and start hunting. 

I would say its completely normal, especially if you know you were very “mobility deficient”.