Joe and Brian,
Thanks for the comments.. I had already downloaded Darrel's instant interrupts but I haven't tried those yet... later in my learning process I will do that. The phototransistor turn off time I'm measuring with a 10K load is on the order of 100 to 200uS, and I seem to be getting very accurate measurements using the CCP1 pin (they agree with my oscilloscope), but not that accurate with the RB0/INT pin because of the things you mentioned.

Bruce,
You nailed it. Thanks for taking the time to read through my code and figure it out for me...I should have been able to figure that out myself, but I kept missing it. I knew it couldn't have been a bad PIC - I bought it from you!