Yeah, i would start with the easy and cheap option too, go and get some Radflush and give the system a clean.
When these overheat though, or the waterways are blocked at all, the coolant normally boils in the expansion tank then dumps the excess on the floor via the outlet pipe.
Then when the bike cools down it will suck the liquid from the expansion tank into the engine, either lowering or emptying the tank, so that's a bit odd that your levels are okay, unless you haven't checked them since it cooled down.
Other reason is if you mix your own coolant with water but have an incorrect mix, too much water and it will just boil like a kettle, which is why i always prefer to use premixed bike coolant.
When these overheat though, or the waterways are blocked at all, the coolant normally boils in the expansion tank then dumps the excess on the floor via the outlet pipe.
Then when the bike cools down it will suck the liquid from the expansion tank into the engine, either lowering or emptying the tank, so that's a bit odd that your levels are okay, unless you haven't checked them since it cooled down.
Other reason is if you mix your own coolant with water but have an incorrect mix, too much water and it will just boil like a kettle, which is why i always prefer to use premixed bike coolant.
More people are born because of alcohol than will ever die from it.