[Vwdiesel] What's going on with my car?

[Tad]

The car: 2001 VW Golf TDI 5speed, 164k.

The conditions: a long drive back from camping- starting with a long dusty
drive at lowish speeds on unpaved roads, followed by about an hour on the
freeway at 75 MPH, followed by 20 minutes at 45 MPH, followed by parking on
the street for a few minutes to pickup some take-out.

The symptoms: when I started the car after sitting a few minutes, the RPM
immediately jumped up to maybe 1500 for a second or two before setting to a
normal 950 RPM idle.  At about the same time, I *might* have heard a soft
"whump" kind of sound (similar to the sound that the antishudder valve makes
a few seconds after you turn off the car) coming from the front passenger
side.

After sitting overnight, the car started and drove normally to work this
morning.

I'm thinking maybe it ingested a bit of condensed oil from the long drive...
but it seems like it would have been a more erratic, longer and/or higher
RPM jump than what I experienced.  Also there was no noticeable smoke
associated with this event.

It's also possible that my big-ass hiking boots were pressing on
the accelerator, but I don't think so...

Thoughts?

Thanks for any input.