I see this expression a lot from LO, granted without the arm lean. She wants to know if you are going to poke, prode, stick something through her nose, down her throat or make her turn and bend in an uncomfortable way. After she has established that you mean no harm, she will either treat you to a big gooey smile showing off her one tooth or an ear piercing scream. She is pretty obvious if she is likes you or finds something about you that doesn't sit well with her. The "experts" leading her baby group have called her selective. I call her amusing.
I am a mommy who like hugs from little ones and funny people. My little baby is 4 but I am constantly searching for signs that she isn't growing up this fast. I am currently in grad school at USC and wonder daily why I am growing up so fast. I also really like cake.