I get pins and needles in my arms when I put them under my head when I sleep, and I get them in my legs if I have been crossing them or sitting with them tucked up underneath me. I have always thought that it was just a lack of blood supply (because you are crushing a vein/restricting blood flow). It is possible that you just have a heightened awareness of it now that you are have a lodger and you are more in tune with things your body does.
I'd probably just wait for the ob appointment, but if you are that concerned, a trip to the gp for peace of mind is no harm