LO is 4 months old. My mom comes over every Sunday to spend time with her. Yesterday she smiled when my mom walked in, but soon after I handed her to my mom so that I could go get something from the kitchen and when I left the room my LO freaked out and started screaming. I know it makes my mom feel bad. She seems too young for stranger/separation anxiety, but maybe not? I don't really know when that starts happening.

How old was your LO when he/she began to recognize and get comfortable with people other than you and your SO?