[Jeeper6]

I have heard some blokes even putting a smear of grease between the two air box sections to ensure it seals.

I too run a K & N air filter Aussiebull with a snorkel. I am heading to the Cape in September to do the OTT plus CREB and I too will be taking out the K & N and fitting a standard paper filter, as well as carrying spares.

When ever I do an oil change, which is quarterly for me, I check the inside of the intake pipe as it has to be lifted out of the way anyhow, and also where the breather pipe that goes in the intake toward the turbo, both have always been clean. There should not be any dust...

AB If you had it serviced prior, it is possible the monkey didn't ensure all 3 tabs at the back of the air box were locked in correctly which would have left a gap for dust...hope not!

As Drover wrote, there would be tell tale dust inside the top of the air box if the seal was not perfect.