That's exactly what it is, confidence. There's uphills and downhills that I am hesitant to touch when I'm clipped in, but when I'm on my "flats" as you called em... I just go for it and if I need to touch here or there, no big deal.
I am noticing my thighs are significantly more sore after each ride though. I guess I did use the push/pull when I was clipped in....
On this note: Should I be wearing some mountain bike specific shoes? I'm wearing skate shoes right now and they seem to work great, but I'm pretty sure there are better options for us platform style pedal riders, which flex less...