That was my first thought too, I hit reserve at about 100 miles which leaves me about 1.2 - 1.4 gallons in the tank. This usually shows to be in the vicinity of 1/4 tank on the gauge, probably just under 1/4 but you get the idea.
If that's not it, I've heard of a couple of people whose vent tube on the tank was plugged not allowing a free flow of gas to the carbs. Try cracking the gas cap and letting her breathe a little and see if that helps.
Good luck and welcome to the site.
I smile 'cause I don't know what the h*ll is going on.