I have to really muscle through the corners because she just won't glide through anymore, and the bike tracks really badly especially coming to a stop on any peice of road that isn't nice and flat.
Pretty common issue. Once I start getting that "weird" front wheel feeling (due to flat spot), I will ride it a bit more to get as much mileage out of it (I don't corner as hard during that time) and then I change it.
6k miles is plenty btw... I'd love to get that kinda mileage