There's no fanfare. There's no fantastic flash of light, look at me, pay attention display. He comes alone, without a show and dance, no host of dancing ladies behind him, and he even uses the door. In fact, it's about as far from normal Q behavior as it's possible to get. Suspiciously demure, subdued in a darker shade of red than usual and even going without his pips and combadge, he might even be mistaken for a regular person.

It's sort of the point.

So he knocks, and pushes his hands into his pockets, waiting for the door to open.