Bumps in the road

I have a 2003 Pathfinder SE with 197K miles. Recently I noticed when I hit a bump in the road my speedometer drops to zero and my abs warning light comes on for a matter of seconds and then the speedometer goes back to the speed I am traveling and the abs warning light goes off. Not sure what is going on. No issues with the braking system but am concerned. I brought it a mechanic who could not find anything wrong.

@Ginsam

Sounds like you have a problem with a speed sensor, or perhaps the connector