Vibration 2012 Sr5 4x4

Gentlemen, got around 1800 miles on my 2012...Yesterday I felt a vibration in the floor and steering that kind of felt like the transfer case was engaged. This vibration was more more noticeable when turning. Had the GF drive as I sat in the passenger seat and felt it in the floor passenger side also. Parked it, went out a little later and same thing. Stuck it in 4WD for 100 yards and disengaged. Vibration disappeared and hasn't come back. No idea what this was and if engaging the 4x4 was just coincidental or what. Could have been a front caliper sticking and that's why it was more noticeable while turning???
At about the same time had the TPMS light go on. When I picked it up new from the dealer in April all tires had 40 PSI. I put them to 30 PSI a few days later as the manual says and two of them were at 28 yesterday. I was able to reset the TPMS and the light is now off, probably not related but thought I would give all the details. Wanted to take it to the dealer this morn but of course the problem went away. Anybody have any ideas, Thanks

 

Bump

Any ideas guys

 

What speed are you feeling the vibrations? I have a 2011 and am feeling what seems like a u-joint or axle bearing or carrier bearing between 50 and 65mph. I feel it in steering wheel and floor, its just a slight vibration, just started about a week ago, truck has 17K miles.