Arm reaching preference

K

I was watching my daughter play (shes 15 weeks) on her piano mat which has toys dangling over her. As I watched I noticed she was only reaching out with one arm. She moves the other one just fine and can bring both hands to her mouth.

Is she just developing a preference or hand dominance... I feel like I'm being silly to worry about her other arm being weak or under developed

Anyone else's LO doing this?