Yes, you would rather not have the sootiness. Markings should be small and as deeply and richly colored as possible without having black mixed in. Sometimes, however, selecting for deep rich color will also get you some sootiness. One reason why Penny was well suited to Shaka is most of the markings behind her are very clear. Milton is the only sooty puppy in the litter, so she balanced him out well in that respect.
As a younger pup, Milton only had a slightly darker face, so maybe he will lose some of that sootiness later, or he may not. It does add a bit to his unique look, and will definitely make him into one imposing big guy later.