It could be a leaking air spring, your air filter/desiccant cartridge, automatic air tank purgers, etc. If you're not familiar with these systems, you should have them checked. What did your air pressure gauges read on the dashboard? Did the gauges leak down after stopping or stay up? You should also check ride height in the back, if the height is wrong it can damage the drive shaft U-joints and bearing in the end of the transmission.
Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI