I'm not sure, but thats what I think it is. Let me explain it a little more. So if I take off really slow it doesn't happen. If I take off kind of fast like on a hill or just need to not take my time, I feel the shifter wiggle in my hand and it has never done this before until I put the lift on. It only does it in 1st and will only do it for a second or so, so thats why I thought it might be driveline vibs.