I've got a 2008 Mazda 3i with 120k miles on it, manual transmission. The brake pedal started going halfway to the floor before the brakes engage, although braking action seems normal after that, maybe a little soft pedal. Brake fluid level looks good, no dash lights are on. I suspect the master cylinder is going bad, but could it be anything else?
This started a week or so ago, after the first snow of the season. When it snows, I like to test the brakes / road by braking hard from 10 or 15 mph after pulling out of the driveway. This time it engaged the ABS (it usually does), so I'm worried it's more than (just) the master cylinder.
Edit: brakes were fine before my hard braking test. Rear brakes were replaced 500 miles ago, front brakes are about half worn.