My baby doesn't like me

SAHM to a 5 month old.

When his dad gets home, he is incredibly giddy, practically falls out of my arms to get to him. I go out to lunch for a few hours and he doesn't even look at me when I talk to him. When I picked him up, he cried for dad.

I know children pick favorites, but do they do it this early? I feel like a stranger even though I'm with him every day.