Well the numbers provided by you all helped greatly.

I started Saturday morning with 35 psi in all four tires. End of first session I checked and pressure was 40 on the left side and 39 on the right side. Car sat for bit before next session and when I checked, there was 37 psi in all four tires. After the next session 40 on left, 39 on right. Being a wise student I checked before and after each track session and each time the same results. Even Sunday with weather a bit chilly I got same results. After the runs 40 left side and 39 right side, cool down to 35 to 37 all around between runs.

Lather, rinse, repeat . . .
Needless to say I never added or took off air all weekend.

Thanks again for the tips.