4wd engaged clunk/thunk

[Hawaiiski]

Hey everyone, I just finished reading the sticky about trans cases differences and I saw that it says to engage your 4wd 1 a month or so. I have a 98 limited with the j case so it's not the center diff lock. When I pressed the 4wd button it worked flawlessly, I could tell 4wd was working by the feel of the steering. I only drove it like this fron my driveway to the entrance to my neighborhood which isn't any farther than .5 miles and I didn't exceed 25mph. When I tried to disengage the 4wd it didn't do it immediately like I expected it would, so I drove out my neighborhood with the button not pressed in and supposedly in 2hi. After reaching about 20 mph I heard and felt a clunk/thunk, when that happened I was like oh s*** and gave me a little scare. After the thunk I could tell it popped back into 2hi after the feel of the wheel, should I be worried about anything? Is there anything to remedy this? Lube the drive shaft and yokes? Check fluids?
When I got back to my neighborhood I engaged it again to see if 4wd was still working and it was but I got to my house there was no smell. Maybe the 4wd hasn't been used in a while? Thanks for the help in advance!

 

[Gerdo]

If you were in 4wd on dry pavement (any high traction surface) and the road has curves in it, the drivetrain will build up pressure and when that pressure is released (usually after turning), there will be a thump. This is normal.

I will exercise my 4wd on longer straight roads. When I come to a curve, I'll shift out of 4wd.

This is normal and nothing to worry about.

 

[Hawaiiski]

Thanks for the quick response, yeah I only did one turn from my house to the entrance of the neighborhood so that's probably what it was. +rep! Thanks!