Well, you have 10,000 kilometers on a front tire, which even if it was still showing lots of tread, had certainly seen plenty of heat cycling, including one other trackday, I assume. This would surely have reduced overall grip, but more importantly, the many heat cycles will have raised the temperature at which the tire would become fully effective, and 2.5 laps probably wasn't enough to get them to temperature.
In future, look at it this way... If a tire is fairly worn, is the $150 you will save by not replacing it worth the expense of replacing your plastics, handlebars, exhaust pipe, tibula, etc? While I will use a tire that has seen some street use at the track, I wouldn't consider it on anything that had seen more than 2000 miles, and I'd think long and hard before using one with that many miles on it. Tires are cheap compared to skin and bone. You can always pull it off for the track day, and then put it back on to wear it out, if your budget requires it. You'll pay a bit for removal and reinstall, but nothing like the cost of the tire itself, assuming you remove the wheels from the bike yourself. A $40 insurance policy. It is amazingly easy to sell used tires on Ebay, too, if you are so inclined. Just be honest about their condition. I"ve heard of used tires with nails in them being sold for more than $50.
In short, I'd blame your tires, especially if other folks didn't lowside in the same place, implying a traction issue in that turn. I suspect you've learned your lesson about old tires, so get back out there and enjoy yourself.
One last little piece of trackside hearsay I'll pass on. I have no idea how true it is, but someone here will probably confirm or deny... I was told that every time a tire is heated up to temp and then allowed to cool, the temperature at which it achieves full grip increases. This means that the more times you heat cycle a tire, the harder it is to get them to temperature until it eventually becomes impossible. I imagine that street compounds are designed so that the temp increase is smaller, allowing them decent life despite hundreds of heat cycles. It also provides a second good explanation for tire warmers. Not only do you have traction on the first lap, but 1 trackday results in a single heat cycle, rather than 6 or 7. I'd guess that 8 hours spent at temp is probably not much easier on the tires than 7 heat cycles, but perhaps it gives a bit of extended tire life. Personally, I've never used them and I still manage to get at least 4 track days out of a set of 208GPs, riding in the bottom half of the fastest group on an Aprilia Mille, 2 days if I also ride them on the street. I always get rid of my tires BEFORE I can feel a decrease in traction, preferring to lose a bit of cash preemptively over losing a lot of plastic.
--sam