Driving home tonight my car developed a new habit of pulling hard about 45+ degrees to the left when I decelerate in gear. It's still smooth and straight under other circumstances and is making no noises or anything. The lower control arms are new, I had the ball joint recall done probably 5 years ago, car has 72k now. It's raining and dark out so I haven't had a chance to really look at it but the wheels are tight, tires aren't low. I had some time to think since I drove that last couple miles to my house at about 5mph and was thinking maybe motor mount or half shaft but I would think there would be some kind of noise or vibration if that were the case. Any initial thoughts since I can't get under the car until at least tomorrow after work? It's parked til I figure it out, the ball joint thing scares me.

before you freak out get an alignment done and see if that fixes the problem.
one bump can fuck up your alignment

and typically the ball joint starts to make loud noises at least a couple weeks before it goes.