Well, I'll give you my take on this subject. It largely restates exactly what skidooboy posted above. That's spot-on.
I will add the fact that you did do damage to the motor. Every engine start does. And no, there's nothing to watch out for and nothing to do to it now. Except of course, make sure it doesn't get repeated.
Assuming that the engine is in proper mechanical order, the vast majority of engine damage (car, motorcycle, boat, etc) occurs at startup. That's because the crankshaft is turning and there's no oil pressure from the oil pump and the metal is cold. It makes no difference that there's residual oil in there. That doesn't change the fact that the plain crankshaft and rod bearings are designed to run on a pressurized oil film the thickness of a few thousandths of an inch. Without this pressurized oil, the metal surfaces are in too close proximity to each other, heat up quickly, and wear out the metal surfaces. Just the way it is.
Prolonged running in this oil pressure state makes it worse. Which is why if the RED oil pressure warning light ever comes on, it should be shutdown immediately to prevent extensive damage. If the pressure falls and stays there, the engine will seize within seconds. Each engine start wears a tiny bit of metal off the the plain bearings. It's really unavoidable. As the bearings wear down, the oil leaks out faster from the thin area that should be there to trap the oil and create the pressurized oil that acts as the bearing. As this pressure film drops, the bearings wear more and the cycle is repeated until the engine seizes or the the bearings come unseated and spin in the crankcase/piston rod. And on interference motors, this usually causes the pistons to hit the head, bend valves, and other bad things.
In extreme cases, this wearing out will cause and engine to fail immediately. In most cases this won't be noticed in the life of the vehicle (since they're wrecked, sold, or other parts fail first). In this case, it could be that the engine lasts 1000 miles instead of 100,000 miles. Aside from taking the motor out of the bike, splitting the engine crankcase apart, measuring the bearings shells, putting the whole thing back together, and starting over, you don't know. So ride on and be sure that you don't repeat this again.