While I was browsing my shops in Sanctuary, I heard one of my settlers mention a "bed problem". When I asked my barman if there was any problem around the settlement, he also talked about the "bed problem", and how it "puts everyone on edge".
I have currently 12 settlers and 17 beds in Sanctuary, so it's not like they have to share a bed or something, yet they still don't seem very happy with their beds.
Could it be because I have multiple beds in the same house, or multiple beds in the same room? Do they not like sharing a room with their fellow settlers?