It sounds like there may have been a hole in the road surface under the new, evenly graded gravel. Your wheel went into the deep gravel at the same time you braked...or maybe something else.
I wear a Hit-Air vest just in case. You do need to be launched off the bike for it to trigger and inflate. The ninja turtle-like chest and back protectors might be best for the non-get-off smash up, especially until your bones regain full strength.
It's not what you look at that matters, it's what you see.
Henry David Thoreau