Accidentally left the petcock on for 5-7 hours last night, what do?

....additionally, even with the petcock fully opened, fuel should be stopped by the carb float needles, and obviously they, or the seats, are not sealing......or level is way too high.   

.......I've forgotten the petcock on "prime" several times, and left it on for hours with bike parked,........and nothing happened as the carb floats did their jobs.......the floats are the first line of defense, the petcock is the backup.

Consider this a sign that you should rebuild your petcock, so it functions as it was meant to. This was written for Yamahas, but the process is similar.  How to rebuild vacuum petcocks

All I can relay is my own experience. In 300,000 miles on KZs I can't begin to estimate how many times I've gone out and found a pool of gas under the motorcycle from the combination of a leaky needle/seat combined with forgetting to turn off the petcock, or failure of the vacuum petcock. Yes it takes a combination to cause overflow. On a good set of functioning carbs, the gas will never overflow.
I can't begin to estimate, but just for a guess I would say 25 times, but I believe more than that.
One thing I can relay for sure is how many times these leaks have resulted in gas in the oil, and that number is zero.
The overflow tubes are 10mm lower than the intake into the engine, so somehow gas needs to rise nearly 1/2" above the drain tubes to get in the engine? How in the frick can it do that? It can't.
So all these years I call BS to gas in the oil for all intents and purposes unless the drain tubes are clogged or the bike stored on its side? Don't know any logical explanation other than those two scenarios.