Thanks fellas. It has been a while since I've ridden an aircooled 2 stroke seriously.
I also listened to a few on You tube and they didn't sound any different to mine. I'm confident now that I am just a worry-wart.
My mechanic from when I raced seriously was always having a go at me about that......
I didn't measure the piston cos it is new, Simo. But the bore measured a max. of 67.030 and the service limit is 67.070, so I figured that was fine.
The best solution might be ear plugs!