Weird...same exact thing happened to me. Got an EF alert for C on a flight ~6 weeks out, saw C7 on EF (all other flights that day were C0), put the flight on hold with intent of ticketing later today, saw your post, refreshed EF, and went to C0, all in the span of about 15 minutes. I suspect it was a temporary "glitch" of some sort that caused C7 to be released...I never see C >3 released on JFK-LAX this far in advance.