It's funny but I was just thinking about Dublinpilots post and he makes sense, but I've found a wierd thing happen as I got more experienced. When I jumped in and out of different aircraft I noticed the differences even more.
I don't find your experience wierd at all, I experienced the same thing.
Probably something to do with less mental capacity being required to do the basics, so the brain starts to process other stuff and you notice things that were not apparent before.
I've only a few hundred hours, so it would be interesting to know if someone with 10 or 20k had the same experience and whether the awareness continued to grow or whether it disappeared again as competence/experience grew.