I brought the car for 55000 miles service, report of small oil leak from the valve cove/adjuster sea

The recommend course of action is going to be to remove the valve cover gasket and replace the cam adjuster seal. So remove the valve cover gasket and the cam adjuster is shown in this picture with arrows pointing to the bolts you need to remove.

http://forums.audiworld.com/picture.php?albumid=76151&pictureid=109980

Put the engine at TDC (there's a mark on the crank pulley) then use VW 3366 tool to compress the tensioner as shown in this illustration.

http://www.80tq.com/~wiz/gallery2/d/1574-2/002.gif

Then you use a hook shaped tool to remove the seals from under it and replace them. You want to go to your local dealer or I can sell you the tool, tensioner gaskets, the special sealant, and the valve cover gasket. Also it's important to replace the PCV valve or suction jet pump as VW calls it so that the leaks won't happen again.