It's normal, especially when you have a sister. Not as certin about your family friend though.
I don't see a problem and the daycare teachers don;t seem to see one. My son was always comfortable playing with girls when he was young. He had three sisters and when they played house they made him be the father.
Hi, I'm going through the same thing with my 4yo son in Kindergarten. Previously he'd played with boys when we attended play groups, but since he started Kindergarten in February, he's mainly stuck with a group of girls. My thoughts have been he misses his 3yo sister and also that he's very articulate and sociable for a boy his age; at a time when his peers don't speak a lot and prefer to do their own, individual thing. I had a family friend suggest he's gay, and that was in January before he'd even started Kindergarten.