Light trap lint would have been long since washed away during the process of developing. However, new particles are introduced in the process and handling (rolling, cutting, scanning, sleeving, etc.) and those will now be greatly magnified. The higher resolution the scan - or pixel zoomed in, the more obvious they become. Lab scanners have no ICE (dust and scratch removal) and some scanners are not as effective as others. For true drum scans, the frame of film is thoroughly cleaned and oil mounted which is part of the cost. Even in making your own darkroom prints you always have to spot the final print. You can look at it like the flaw in the diamond, it makes it natural instead of man-made . . .