Sorry to dig up an old thread, but this is exactly what mine is doing!
First did it on a long run about 9 months ago, change down, change up again, went away.
Haven't noticed it for ages, but did it again tonight on the way home.
Strange thing was, at 3000rpm it seemed fine, drop to 2500rpm for 30 seconds or so, and the 6 started flashing. Change down/up, accelerate, 6 on constantly.
My clutch release bearing has been noisy since I've owned the car (coming up 3 years), as the clutch was only worn by about 20%, dealer suggested putting up with the squeak until the clutch needed doing. Nearly three years later, clutch still fine (for now....) and loathed to replace a half-worn clutch just to fit a new release bearing. Unless this is something related to the flashing 6, and a potential cause of future heartache?
Any ideas anyone?