I've noticed this last year that my valve cover and air filter housing are getting a little more oil and crud on them, and its coming from the tubes that run from the valve cover to the air cleaner housing. Is this normal? Seems to be a little spray that builds up over time, but lately it seems to be a little more. Just wondering. Everything works as it should.

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1984 300D turbo, 250K
1971 MGBGT, 101K
2007 VW Jetta, 4K