Experienced this for the first time during my ride yesterday. I hit some - well, I guess you might call it - severe road turbulence of the type that caused the bike to literally rock back and forth (just like a kid's rocking horse) as first the front wheel and then the rear became momentarily airborne due to repeated bumps in the road.
No serious danger of damage or of taking a spill - just a momentary rough ride.
I noticed that the jarring action caused my chain to momentarily disengage with the rear cog causing me to skip until the RD was able to take up the slack.
Is this normal or is some sort of adjustment in order?
The bike is otherwise operating at its optimum.
FWIW, I run a double chain ring with a 9-speed cassette.