Rear Differential Paint?

Driving down the road, I am always inspecting, admiring, etc. other tacomas (who doesn't?) and have noticed on the rear differentials sometimes there is a white paint around the bolts. What is this? Is it some kind of sealant? I recently changed my differential oil. Did I forget to add this?

 

Was it lines on the bolt head and the rear diff? If so then it's just showing that the bolt has been tightened down and that is the mark it should be at, if not then i dont know bud

 

No just a white paint that looks like it was spray painted around the bolt. Wish I had a pic...