It is a very common experince, I'd say. Sometimes, the stuff I do just seems to go so well, I know exactly how to deal with this and that etc, and I think "D*mn I'm good". It is quite a good feeling actually.
I had the same feeling when I was cooking food for a living too, sometimes. But I did very well know that I was no star chef, or even worthy of peel the potatoes for one. I just felt I was doing great with what I was supposed to do right here and now, and everyone was happy.
It is the same with computers, I *do* know that I know very little of what there is to know, still I sometimes feel like a great programmer. It is one of the rewards. :) You have the right to remain delusional for the next five minutes.
When you are very new at something though, you can easily imagine yourself being the programmer (or star chef for that matter) in just a few months, because you are almost there, being that good. Haha. Then reality pops up and tells you how things work, and after a few such experiences, you are accustomed to reality.
Also, when you are new, you learn stuff much faster, because you learn so much. Everything is new, you learn a hundred things a day. Now you learn two new things a day. Of course you get hubris when you learn so much so fast. :)
And never forget, that certain kinds of hubris is considered a virtue among our ranks. And this is one of the good kinds (unless it turns to boasting or a personal cult of course) - it allows you to think you are good enough to do something, or get that job, or whatever... and probably succeed. Within reason.
You have moved into a dark place.
It is pitch black. You are likely to be eaten by a grue.