[vectorit]

Personally I'd be concerned.
I have the odd habit checking parts like this after a drive, mainly because my truck is a 40+ year old rig and things just happen. Recently I was doing this check after a drive, and found that one of the rear hubs on my Eaton was very hot. Later I took the axle out, and popped the drum off to find a bearing that was blue. I blamed it on myself for over tightening it, but if I didn't check it - it would have eventually failed causing more damage.

What kind of hubs do you have?
OE or aftermarket?
Have you had them serviced recently?
You could have something getting ready to seize up or come apart.

I'd take them apart and make sure everything looks good, and that there isn't any petrified grease in them.