Don't feel alone; I have been playing with this language for 10+ years and I keep running across something new and wonderful every day.

When I'm asked to rate my Perl knowledge during an interview, I say that "I am a 7.5 out of 10 -- I know the basics fairly well, and some of the more advanced topics; but I also know that there 30% of Perl that I've never used before. However, I do know where to go to read up on what I need to learn about what I don't know." This sometimes (quite often) segues into a discussion about "how do you know what you don't know" and completely derails the interviewer for half an hour or so.