Heh, I thought you were talking about waking life OP.

Anyway, that brings a similar point across. Even in waking life, when we read something, and then re-read it, we often find that we missed bits, skipped bits, sometimes even totally misread bits.

I think it's because of a changing perspective, filtering things out. That of course applies to dreaming, even though in dreams something 'physically' changing is of course very easy to happen to. Regardless, in a dream it is still a projection of perspective.

Your perspective constantly changing, what you see is going to obviously change, as well as the totally projected environment of dreams being directly altered through that.