Take it easy for awhile to let the studs 'set', and then don't worry about it if they've been properly intalled. Haven't noticed any missing studs on my Cooper M+S, they're on their 3rd season now. I was looking for some studded Hakka LT snow tires but couldn't find any and settled for the Coopers. They've done ok on everything except water covered ice, which I guess was ok as no one else with studded tires was doing well either, as after chaining up all that I saw on the back roads heading home home were large 4wd vehicles with chains. I'll probably get the Nokians next time though, as both Taurii with studded Hakka 2 tires did fine (the truck with the Coopers did fine too) in the last storm, when others in 4wd trucks and SUVs here in the Portland area were making the national news. I saw a fair number of trucks and SUVs chained up, which I don't see around here very often, and also a fair number sliding sideways and backwards thru parking lots and on roads.
If I did it over again I'd make sure that the dealer installs the proper studs, the Cooper M+S seems to take a heavier stud than typical tires, and I'd even look at finding some 'rally studs' with heavier tungsten studs that aren't oversize.