Does your airplane make the book numbers for takeoff distance at higher altitudes?
I got surprised at Big Bear (L35) last spring when my takeoff roll was far in excess of what I calculated from the POH charts. The same thing would have happened later that month on departure from Spanish Peaks (4V1) if I hadn't reference my Koch chart for a conservative backup set of numbers.
Are you seeing book numbers, or close to them, for your takeoffs at higher altitude airports? The charts say that the no wind takeoff roll shouldn't exceed 1500' at 10,000' pressure altitude and 30 degrees C, does that fit with what you are seeing?
Cheers,
Rick