Strange cam lobe wear pattern

Hello! Just thought I would present this for everyone to ponder. I have a 1982 KZ1000J2 with about 17,000 miles on it. The bike runs great, an absolute blast to ride. I recently re-shimmed my valves and noticed this pattern on the peak of three or four cam lobes, some intake and some exhaust. The surface of the lobes are smooth, no grooving or pitting. I put everything back together and have ridden the bike since with no trouble. Just wondering what that annular pattern could be, heat maybe? I'd appreciate some insight. Thanks!

Cams are made in sand cast molding or forget in shape, so some unnessesary surfaces don´t need to be machined. Your cam looks perfect btw.

Right, I understand what you're saying. What I'm concerned/interested by is the oval ring pattern on the very top of the cam lobe. I don't know if I've ever seen this pattern on another cam lobe. I've included a better picture of what I'm talking about. 

This oval ring pattern is cause by the rotation of the shim/bucket under pressure at high lift. The valves have to rotate in little steps on every lift to prevent hitting into same position of the valve seats in the cylinder head. How do the shim surface look like?



 

Cool video, it's always crazy to see the valves working at mach three! The rotation explanation makes sense, but it's also bit puzzling because only three or four cam lobes show this pattern on their points. All of the shims look good, and all shims show a rotation pattern on the top face. Also interesting; when I last adjusted the valves about two years/5,000mi ago, I do not remember seeing the oval patterning on the cam lobes. I'm not concerned about it at this point, just really curious as I've never seen this on a cam lobe. I love learning about things like this!

Looks like the valves lap themselves at 14k RPM 

I thought the same thing when I watched that 

Without having the cams in my hand to determine whether the hard facing  is wearing through there are several reasons that may be responsible .
1. Incorrect valve clearances.
2. Excessive valve spring pressure.
3. Insufficient lubrication due to poor quaility, wrong grade/type of oil or oil changes too infrequent.
4. Incompatibe aftermarket valve shim material.