I have an 04 545 with 60k on the odometer. This same problem has been ocurring for 6 months. I have brought it to the dealership 3 times, and the first 2 times they could not replicate it.
They finally did and say it needs a new "valve body" which is about $5K for parts and labor. I am now trying to get my 3rd party warranty to cover it, and having no luck.