Re: Faster than expected load
Should you be concerned? Possibly.
There are a few things to concider.
1: Make sure your chony is consistent with another chrony.
2: It is very possible that you can see 150 FPS of difference between rifles with the same factory ammo. Even the 308. Even more so when you handload. One lot of powder can be much hotter than another. Add a rifle's unique character and you have a huge variation in pressure/speed.
3: Near 2800 FPS with a 175 is a pretty stout load for the 308. That said, with a good barrel length, proper chambering, quality barrel, and the right powder, 2800 is not out of the question but its getting there. I have pushed the 178 as fast as 2850 in the 308 with notellum powder without any sticky bolt lift or cratered primmers but it was still a very hot load. Safe or not, it is hard on barrels.
I wont tell you if you should or should not change your load. If it were me, I would verify my chrony was not screwed up. If not, then I would drop my charge a bit to lower the pressure till I found the next good zone of accuracy. There is really no point in tearing up your barrel from high pressure loads. Everything has a price.
Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.