Vibration and grumbling is back again

Well it seems to have started again.

The last time it occurred in 3rd gear under engine braking downhill. That was about 3 months ago and only the once.

This time it happened under normal driving in 3rd and 4th gears.

It manifests as a low frequency vibration, grumbling noise and the gear lever vibrates along with it.

At first I thought the gear might not be properly engaged so declutched and into neutral then reselected gear. Fault still there.

it lasted for a few minutes then the car drove normally and it hasn't happened since.

This is now happening on a regular basis.

I'm thinking it may be gearbox / layshaft related and will get it booked in to be looked at when we get back home. Unless, of course, it gets much worse while we are away.

I do have fingers crossed.

Anyone had anything similar?

Edit: dealer's looking at it today. I hope they find the cause ??