Is it normal that i like that i am smarter than my girlfriend?

My first girlfriend was too bossy and too much of a feminist. She hated it when me or anyone else challenged her, and always felt threatened if her man showed an ounce of knowledge more than her.
My current girlfriend is the exact opposite! First off, she is NOT a bimbo! She doesn't have the ego to be a bimbo. She's real hot but shy and modest about it...not arrogant at all. Bimbos are arrogant! However, is it wrong that I am attracted to her submissive, simple-minded nature? She is very smart, but I feel masculine and powerful when I need to explain something to her she doesn't understand. Is that normal? At times, when she doesn't get something, I am turned-on when her mind is very child-like about it and she needs it carefully broken down and explained to her on a level she understands. Is it normal to like that and be attracted to that?