Mild random engine rev flutter while idling

[Rissy]

I was out today giving Lex a wee warm up engine run in the driveway just now, and out of the blue without me even being in the car, after idling for about 15-20mins, the revs suddenly climbed, not too high, definite engine tone increase though, and then after a couple of seconds, returned to normal again, then a few seconds later, did the same thing again!? Then it was ok, at least for the 5mins following until I got her back in the garage. If I had to estimate the increase amount, I'd say about 800-1000rpms...

Anyone else had this before? Is it a sign of something bad impending?

[Guinney1971]

possibly something in the fueling system self adjusting due to the car not being run for a while.

I doubt its doing any serious damage, best to take it for a short run and see how it is afterwards.