Can also be the H pipe itself.  I've seen H pipes leak at the tiny seams.   Hard to see with the naked eye.

Wipe everything down dry with paper towel, then start engine and look for leaks once system pressurizes....or better yet use a cooling system pressure tester to find the leak without engine running.

VW no longer sells 1.9 H pipes.  Gotta use a used one or the VanCafe.com repro.   I have a couple of good used ones in SF if you cannot find one locally.

-Paul