I got my invite late as well, and am hoping sonsofanarchy is right about the late invites coming due to matching. I will say that I was really impressed/flattered by the alum match - they matched me with someone in a specific industry I discussed in my essay (an industry that I don't think many Stanford alums are in). Sadly I had changed locations and wasn't able to meet with him, but still really appreciated the thoughtfulness of it.
I had 100% given up hope on the 25th, and that made the invite even sweeter

Now back to the waiting game. Congrats to everyone else who got invites, and everyone else keep your heads up! Harvard dinged me with no interview so I'm thrilled for the shot at GSB.