I know it sounds weird but this one day last week and this morning when pulling up to a junction (the car had been running for less than 5 minutes) I noticed a slight 'shivering' going through the car. The rev's weren't dropping and the idle was stable but it seemed to be shaking a little.
Once I was away and up to speed this stopped (and the car was warm at this point) it didn't happen again.
What an odd little quirk - SHE'S ALIVE I TELL THEE, ALLLIVVVVEEEEEE!!!!