Weird things like that can mean nothing or genuinely affect the long term health of your plant, and the only way to find out is to take good care of the plant for a while and see what happens with the new leaves. If you're concerned about something contagious, try to quarantine the new plant.
If you're not sure what might be wrong, you would be acting imprudently to blame the seller at this point. To my eyes the brownish areas look older than a couple of days, but who knows really.
One thing above all to respect and understand is that Aeoniums have an annual cycle of growth (fall through spring) and rest (summer). Late summer (sometimes into early fall if it's hot) is when they are going to look their worst and be at their most sluggish, guaranteed. Here's a picture of another variegated Aeonium at the end of summer... those black spots are of zero concern to me except for aesthetics, because I know from experience that they're a temporary thing the plant will grow out of.
The other plants around here look worse actually because they are not receiving any protection from the sun.
Your Aeonium may change radically and look quite different in a few weeks, so give it good light (like indoors right by a sunny windowsill) and see what happens. The key thing to look for is whether the new leaves are healthy or diseased.
