Ahh, thanks a lot Gabriel! "Auto brightness", God dammit!!! I just had a look at the two baby pics in the scanner's preview, and sure enough: the second one is a little darker. Adjusting the brightness gives that noise like texture, more than when adjusting the curves. Hmmm, wonder what the difference between the two actually is...
Anyway, I think I got my answer here, Gabriel. Thank you very much!!
Arnulf