And? Jane Lynch was a recurring guest star on Two and a Half Men before she went on Glee and I can remember seeing her a lot more than I ever saw Henry Polic II on Webster.
What's funny is that I was considering getting all adversarial about this, considering the source, but then I actually did the research.
According to IMDB (yeah, yeah), HP2 appeared on 54 episodes of the 150 episodes produced. That's pretty much the textbook definition of a recurring character.
I don't think anybody's arguing whether or not he was a recurring character...my point, again, is that some are more memorable than others.
Hell, I watched Diff'rent Strokes every day for about five or six years when I was little and I didn't even know that there were two other maids after Mrs. Garrett until years later when I started watching the reruns again. (only one of those, technically, can be considered recurring I think)