Please note that these aren't mutually exclusive options.

In May I bought a new-to-me 2007 America with about 12k miles and pretty decent service records (serviced at a dealer in Indy). I put about 300 miles on it then promptly went overseas to work for 2 months. When I came back there was a dark circle of dried fuel about the 14" across directly under the bike. Pretty sure it leaked out the carbs, but everything is dry now, so it's hard to say more directly.
After a couple discussions with better diagnosticians than myself they both said "probably needs a carb rebuild" but I also discovered that I left the petcock open with an 80% full fuel tank (in a non-environmentally controlled NJ garage while it was ~95 degrees most days, under a heavy cover).

I took the bike out into the driveway, cleaned it off, turned it over and it not only didn't burst into flames, it ran like a champ. I took it for a couple short rides after letting it cool off each time, closing the petcock each time. No detectible fuel leakage.

So my question is, do I really have a problem with my carbs that requires a rebuild? Or am I just a dummy for not closing my petcock? What are some other symptoms I can watch for? The last time it looks like the carbs were touched (and documented) was on delivery. Jetted for Short TORs.

I previously owned a 2007 America and hardly ever closed the petcock and never had a leak. I also rode that bike hard and sort of neglected it, but I'm much older and more responsible now....trying to take better care of my things.

If it seem s to be running OK, you probably don't need to do a "carb job". You might ad some fuel system cleaner to your next fill up. I would be worries more about the fuel that leaked through the carbs in to your head and then in to the crank case. You might want to do an oil change.

I had a similar event. One of my nephews started my Truxton up to show his friends what my new pipes sounded like. That was at Christmas. He forgot to shut the petcock, in spring I realized that a near full tank had had emptied. My dealer told me to change the oil, sure enough the oil smelled of gasoline more than oil and had the feel of veg oil.

The tank has a vent hose and the leaked fuel, caused by heat expansion could very well be the causation of the fuel loss. The vent hose does terminate very close to your described spot on the floor. If you have doubts about your oil, change it.

I wouldn't have started it without an oil change first just in case. I have ALWAYS turned my fuel off when parking and back on most of the time when I leave. Good habbit to get into with a carb bike.

Good advice Ian.

On my 2004 Speedmaster I never turn the petcock off and I have never had it leak. I know you are supposed to turn it off, but I never do.

What happens is a float valve being open or leaking for a long period of time with the bike on the kick stand.
This is what happened to my 04 Thruxton, near a full tank of fuel went in to the head, crank case and exhaust. Yes there was a puddle of fuel under the bike.

Oil is being changed today! Good advice guys.