I tend to understand things rather quickly, but after 2 years of programming in Python I still stumble across things (like Flask today) that amaze me. I look at the code, have no idea what's going on, and then feel very humbled. I feel like an absolute expert each time this happens, up until the moment it happens. Then, for about a 2 week period I feel like an absolute beginner.
Does this often happen, or does it indicated that I have so much more to learn before I can even be considered a "good" programmer?