My wife's 2008 4 speed had a similar issue, turned out to be a loose (very loose) shift linkage bolt on the transmission.
Just 1 possible cause but definitely worth checking before you spend any money.
Just a heads up, if it kicks back like that round a bend on the hyway (wet road), it's extremely likely to cause your life to flash before your eyes, even on a straight (wet road), your going to s**t yourself.
I wouldn't drive it but at the end of the day it's your call.