Believe it or not, I can support the OP's claim. I was playing around and taking pics with my iPhone and it did do some sort of zoom randomly. Upon taking a picture though, it was captured at normal size (no zoom) and then everything returned back to normal. It was a little awkward but i just ignored it, and it hasn't happened again yet!
Thank you! I know I'm not going crazy here... If it does happen again, I'm coming back here just to take a picture of it.