Ok, first off... if it was "stuck" and wouldn't rotate then something is wrong... ignoring it won't make it better.
I don't think you cold seized it... cold seize happens when the piston expands faster than the surrounding cylinder walls. That requires some hard throttle like jumping on it hard right out of the parking lot. Pulling it out of the garage would not be sufficient to do that.
You could pull the plugs and get a bore light and look down in and see if you see scoring on the cylinder walls, that will tell you if you have a piston dragging funny.
Do you keep your sled clean under the hood or does it look like a grease pit? I'm not being an azz, I've seen both sides of it. If you don't keep it clean, you could actually have had something get down in the pull starter and bind up the flywheel. I think this is remote.
Now for the ugly propositions... I've seen this happen on other sleds like you describe. Motor is running, then stops, won't pull over. You fiddle with the clutch and it spins free, starts and runs. The cause every time was a main bearing on the crank coming apart. The ball bearings in the individual bearings are spaced apart with a little spacer ring with fingers on it. Those fingers break off, allowing the ball bearings to move closer to each other... they will bind up and stick the crank. You wiggle the clutch and then free up.
How many miles on the motor?
I'd start by inspecting the cylinders, either via bore light or even lifting the head and taking a look. Then I would look and make sure nothing was binding on the pull starter side. If I found nothing obvious, I'd be pulling the motor down and checking the crank.
Give this post a day or two, the 900 guys will jump in with some additional advice I'm betting.
sled_guy