You were probably wise, or lucky to have missed it. Unfortunately the moonbow has somewhat gone the way of the firefall...something that used to be fun but is now a sea of photographers (looking very serious and protective of their territory that they stake out hours in advance) with massive tripods and pricey gear. Over the past 6-7 years I've watched it get more and more crowded, and I can't imagine what it would have been like on Saturday night.
I was there that week, but left Saturday morning and it looked like a mile of cars lined up at the 140 entrance, about 11AM on my way out. I did go up to the fall on Friday night, and there were tripods lined up solidly along the back, with intent-looking faces protecting their spot while they discussed lenses etc. We plopped down right behind the rocks, I put my little camera on a shortened tripod, and had a good time while we waited. The moonbow was not spectacular in comparison to some years, and I doubt that Saturday was any better since there was a limited amount of mist.
This one, shot a little earlier, looked too much like daylight for me, but shows the bow up a little higher where it first appears.
On Friday there were a lot of folks who just sat down and enjoyed it, but I would imagine Saturday had a forest of tripods covering the whole area for the lower fall. I assumed the upper fall bow on Friday would be either minimal or non-existent, since there wasn't a huge amount of mist, so I didn't check it out.
Anyway, if you're trying next month, if there's enough water, the best nights should be a Sunday or Monday, so the crowd may not be so bad. But unless there's a bit more snow, the fall may be too small (last year it snowed on us in the valley in mid-May, so it's not impossible).
While it's fun to go there and try to get some photos, I don't get the seriousness of some of them that attend. These things have been photographed so many times that there's nothing original... it's better just as something to do and have a good time.
Gary
Yosemite Photo Galleries: http://www.pbase.com/roberthouse/yo