Really? I did two tandem jumps from a prop plane and definitely had a brief "falling" sensation.
Around jump 120 or so I was helping a buddy obtain his tandem rating and did my one and only tandem with him and did not experience any falling sensation.
The a/c is traveling around 85 or so mph, maybe faster for some platforms. Terminal velocity for a skydiver or tandem under a drogue is about 120. I'd estimate a tandem without a drogue is around 160. Leaving the a/c at 80-90 mph and transitioning to terminal takes about 4-5 seconds.
What is happening in that time is that you don't drop straight down. You travel with the a/c, slowing transitioning from horizontal flight to a vertical fall, all the while accelerating over this 4-5 second period to your terminal velocity which means you gain that 40-ish mph in that 4-5 second period.
In short: I don't know how you felt anything but prop blast. A drogue-less tandem could in theory give you a slight sensation, but you are looking at a second or two, maybe, but your body s still dealing with the forward throw of the a/c.