Thanks, Jack. I'm not totally surprised. If the voltage from the FSR when not pressed is quite high (eg. 4V) and when pressed is quite low (eg. 2V) then that effectively could be treated as a digital signal, because the digital inputs would have a "transition" zone (around 2.5V) where above that is considered high, and below is considered low.
Indeed, I've measured it, and I think the FSR is darn near an open circuit with no load (weight) on it, so I'd bet the pin is very close to Vcc (the project actually runs on 2xAA alkaline cells). Since the FSR actuations in my project are quite slow, I did use a fairly long debounce interval on it (100ms vs. 20 or 25 for the buttons), but I'm not sure that is really of any consequence. Just one of those serendipitous things, it still makes me smile
I used this FSR from Sparkfun if that makes a difference to anyone:https://www.sparkfun.com/products/9376