Yeah, we didn't dwell too much on the episode numbers, and certainly never referred to them as such. After "Episode IV" appeared in '81 (probably didn't actually see it until home video) we just assumed we missed it or didn't notice it when we saw the original back in '77. Then after seeing that my friend's Art of Star Wars book attributed the Episode IV designation to a 1976 draft of the script, we were convinced. (Was this George's first step in creating a revised history??)
Back in the day I always thought it was neat that these movies were set in the middle of a larger time frame, without expecting that any more movies would ever be made.