Mine appears in low temps (didn't hear it all spring, summer, or fall) at 40-55mph especially under deceleration/coasting. The part where mine is a little different is that I can go into 4WD and come back out and the noise will be gone for the remainder of the trip sometimes.
Mine does this sometimes (maybe 20-25% of the time)... The road to our neighborhood is a long straight one w/ a 50mph speed limit so I've gone up and down in many times switching on the fly between 2wd/4wd and have noticed it not immediately return sometimes. I'm still fairly set that it is the needle bearing going bad (or having gone bad already I guess), and hopefully will get a chance within the next two weeks to have it installed