Won't crank?

Mike I'd say if it does it again and you pull the plugs and it spins right over that sounds like hydro lock. In other words water in the cylinders. That's what I usually find when I hear the starter make a "clang". Something has the engine locked.

That could be caused from something as simple as leaking intake gaskets to something worse like head gaskets or even worse yet like a cracked head. Probably not that bad though since you didn't mention anything about overheating problems or puking out coolant. Maybe try tightening up your intake bolts and see what happens. Hopefully you'll get lucky.

When it sits overnight something could be leaking down into a cylinder causing the hydro lock so when you go out the next day to start it all you get is the clang.