maybe it wasn't full when they did the change. Also check for filter/drain plug leaks, it's possible they didn't tighten something all the way.
I lose around 1-2 quarts between oil changes (6-8K miles) and only lose it on long road trips, i'm not sure if i'm burning or leaking.
2 qts in 2K miles is a lot, but you need to set a new baseline and monitor it from now forward. Fill it properly and follow the leakage patterns. I always check mine at least 1-2 times a week, and always before and after long road trips, and before and after any planned hard driving. If it continues to leak that amount, take it back to the dealer. I've taken mine back with my losage and they couldn't find any leaks.