It never really made sense to me before as to how this whole thing worked. But this year I actually participated in judging. And now having done that, it all makes perfect sense. To the OP, so help clear things up a little:
Basically in a category with a large number of entries, it would be too much for one set of judges to judge them all. So they break it into sub-panels. Each consisting of usually 2-3 judges, and each managing a smaller, much more manageable flight. The two sub panels judge their respective flights completely seperate of each other. And then after those are done, the best 3 beers from each sub panel go on to the mini BOS. (yours undoubtedly went this far with a score like that). For the mini BOS, they usually pick the more senior judges from each sub panel (in my case we had 2 sub panels with 2 judges each, and 3 of the 4 did the mini BOS - I didn't get to participate since it was my first time), and they taste all the mini BOS beers and decide which is "best". At this point, there are no scoresheets, names, anything. Just an entry number assigned to each beer. It's possible at this time that the the beers from the other panel were better than yours, or that judging them side by side made some stand out more than yours, etc. There are several different variables at this point - remember that in a flight the beers are not judged side by side but instead back to back, and this can influence the judges perception of the beer. Things like flight order, pallet fatigue, etc.
Hope that helps to clear it up a little. I know it did for me.