My first question is 'why was this bearing removed' (since it had been installed less than a year ago)? It looks to be well-greased; I'd clean it thoroughly and have a close look at whatever you can see on the outer part of the inner race, 'across' from where the discoloration occurred. I agree it doesn't look burned; this may be just surface corrosion. If so, I'd want to figure out why it corroded in under a year; what does the spindle look like; i.e. is there any corrosion, pitting, etc. where the bearing sat? What does the bearing and spindle look like on the other side (of the car)?
If nothing obvious turns up, and it's just surface corrosion, and you can determine what caused it I'd be tempted to sand the corrosion off and re-install. I know, the adage is "If you've gotten it out, might as well replace it with new," but with the 'quality' of some aftermarket parts these days it could be better to reuse an older, better one. My experience is that, in attempting to be the part that shows up first in a 'search by lowest/increasing price' internet search many companies are skimping on coatings and corrosion protection (anybody bought any really good repop chromed parts lately?)