Yeah, sadly, they were bots. They all did the exact same sequence, which I assume someone recorded, as they used the exact same url and session id. So I could have just blocked that, but instead wanted to go with something a bit more stable since someone took the time to record the posting method for this site.
Honestly, I didn't know this site actually got hit as bad as it does. I'm surprised my little "guest posting" checkbox lasted as well as it did.
Sorry it took so long, but real life has been busy, and these forums have ran so well over the past few years I never have to worry about it.