I think it's real load, although I really don't know why. My brother is coming to visit this weekend, and I currently have him on the 6:45AM flight on Monday. Since that's unbearably early, I was hoping to switch to something else (any of the 4 later flights in the current schedule), but it's been zeroed out for a few days, and very heavily loaded prior to zeroing.

I've seen this happen once or twice SFO-BOI over the last 4-5 years, not sure what drives it though, and to be fair this is for a longer duration than I remember.