I recieved some new wheels. The hub is shamano (red in color if that matters). I installed my 10 speed cassette from my previous set of wheels to the new ones. I got the lockring tight and the whole cassette wobbles on the hub. It appears that the hub is longer than the one on my previous wheels. The lock ring is tight before it touches the 12t sprocket. Did shamano make any changes, or is there some kind of spacer i need? Any help would be great.

Yes, there is a small spacer that needs to be installed behind the cassette on all but 10 speed specific freehubs.

I read somewhere that there's a thin spacer you have to use behind the cassette unless you have a 10-speed specific freehub body.

Do I just get this spacer at the LBS?

You should have got that with the cassette, however, you should be able to get one at a bike shop.