Vibration at 1000 revs.

[MrSambambles]

Hi All. First time of posting so hope this works. Got an annoying vibration at about 1000 rpm. Car 1 year old with 3500 miles. Took it to main dealer for first service yesterday and asked to be investigated. They could not find any problems. Its not loud but so annoying especially
in traffic. Its not at tick over but just above and goes again at 1100 rpm.
Do any of you good folks have any ideas as to what it could be.