do any of you with the weber gas grills get a loud popping noise as the grill heats up? I understand the concept of metal expanding, but this is a pretty loud pop and the flame even flickers when it pops. I had weber send me a new manifold but that didn't solve it, so maybe it's just the metal? It eventually goes away, or strongly diminishing, but it's bothersome. I held the phone to the grill and the weber rep said it didn't sound normal, thats when he sent the manifold. I never called to tell them it didn't fix it b/c they didn't have too many ideas the first time.

Sounds like the propane regulator to me.

Sometimes that also happens if your tank isn't purged prior to filling or refilling.