My girlfriend and I have a bigger gap, though she is a little older than 16.

However, I know a lot of older couples (say, in their 30s or so) that are 11-12 years apart. It's not the gap that people have a problem with, but the ages.
But, hey, love has to start somewhere, right?
...So long as either person is of the proper age...though. I don't agree with children dating adults.

I don't think you're creepy. :o
I hardly even consider 16 and 20 a big gap.