Car is '97 E420, 86k miles. Driving into work this morning, going about 30, the transmission acted like it slipped into neutral. (The gearshift was not inadvertently moved.) This was not a "partial slip" as if it was a little low on fluid - the engine became totaly decoupled from the wheels, like it was in neutral.

I let off on the gas and moved the shifter from D to 4th and back to D, then everything was fine - I drove one more mile to work.

This transmission has never had a problem, except for a little sloppy 1-2 shift during full throttle acceleration.

What am I likely looking at here? Is it going to leave me stranded? Thanks