Why did my dirt bike shut off?

hi i have a 1980 honda xr80 4 stroke and today i was riding around a i took it threw a ditch with a about a 1/2 foot of water and as i was climbing out of the ditch my bike bogged right out and shut off. so i went to start it again and it wouldnt for about 20 minutes. i did a oil change about a week ago and there is not water in my moter i checked and my air filter is clean and i had it about 3/4 throttle. its probably nothing but im just wondering if i need to be worried.