Do they know???

Very long post I know...

Okay so my little girl is almost 4 months old (on May 12). Yesterday I went to work at 8 am (she was asleep when I left) and then as soon as I got home I got her ready real quick to go to her gparents house for a few hours while I went to play bunko with my mom and some others.

I picked her up afterwards and she was sound asleep, so I put her straight to bed when we got home.

Basically, I hardly got any time with her yesterday.

So, then today my husband said she was fussy all day long. Did not smile or anything for him. BUT as soon as I got home from work today and she saw me, she was all smiles and has been in the best mood!!

So my question is, do babies that young know that their momma isn't there? Can they sense these things??