No reply on Cycle Chat so let’s see what the collective brains of STW can come up with.

I had some loud clicking and clunking from my BB area so I took out the BB30 FSA cranks and found everything filthy and manky with quite a bit of grit around. I was surprised to see signs of erosion on the surfaces of the BB axle that fit inside the bearing inner races, despite them being a snug fit. However against my expectations the BB30 bearings were in good nick so I left them (had bought replacements at my local bearing stockist for £4.95 each) and cleaned everything up before greasing the surfaces with Copaslip and reassembling. The service has cured the clicking and clunking but I have two questions:

1 – I torqued the 10mm bolt to 40nm as instructed then rode the bike up the street and re-torqued, finding that the bolt turned by around 45 degrees before the torque wrench clicked over. This afternoon I rode 40 miles and then rechecked the bolt and it turned another 5 degrees or so. Is it normal to have to re-torque this bolt two or three times as the two parts settle together?

2 – What causes the small areas of erosion that I saw on the machined surfaces of the alloy BB axle, where it fits snugly inside the bearing inner races? Should I worry about this? It is definitely pitting rather than scoring or polishing from fretting.