Do you know what they were in there for? Maybe there were in there for repairs rather than just oil changes. They usually have separate technicians who ONLY do oil changes so thats why its usually pretty quick. Its not like theyre going to get their master mechanic in there for an oil change. Hence why I take my oil changes to my local mechanic, ill pay more but ill know the job was done properly. But if I were you, I wouldnt sweat it.