Good question 333. Funny.
If another bike was low on gas, I might have taken some if I needed to get somewhere -not too likely, but it's a maybe. I wouldn't leave it at or below reserve for someone. If it was a friend, I'd most likely fill her up as a friendly "this round is on me" gesture. If it was old gas, I'd drain it for the lawnmower(mine will run on anything -old 2 stroke mix gets put in it) and put a couple gallons of fresh gas in.
I'm spending too much time thinking of the scenarios here. You're alright.
Edited to add: As far as signs of the times, first quarter profits are reported as Chevron $5,170,000,000. Exxon Mobil $10,900,000,000. Shell $9,080,000,000. BP $7,600,000,000. I think I'm going to try for a job in oil.