Sleeping less in crib

Katie
My 11 week old son was sleeping 6+ hour stretches consistently in his rock n play in our room. We decided to move him to his crib before I go back to work since our bedrooms are connected and we are still very close by. Now he is only sleeping 3 hours at a time. Any advice to getting him back up to sleeping longer stretches? Has anyone experienced this in a transition before? How long did it last?