Dirty oil from final drive

[Dodgy Rider]

Hi all the bearings in my final drive collapsed last year and I had them replaced by a local chap. All the bearings and seals inside I got them from Motroworks all new. I have now made about 3000 miles when I decided to replace the oil from the final drive to make sure nothing weird came out. The oil came out dark grey. The chap who did the job thinks it may be residual grease from the bearings since they were new and the heat has disolved it in the oil. (The oil I used was clear by the way). I noticed in the oil that came out very fine metal particles that I managed to isolate with a strong magnet. There are just a few but very fine. My question would be, if someone had the internal bearings replaced, if they found the same issue. Is it normal or is there something wrong going on inside?
Many thanks

 

[Mzokk]

The identifiable metal particles would make me wonder? My bike is on the original FD bearings at 82,000 miles. I change the bevel oil annually and all I get (so far!) is a tiny amount of grey metalic sludge on the magnetic drain plug....no identifiable bits of metal as such and the oil looks much as it did when it went in. Only about 3,000 miles a year on that bike though.