Do you think newborns see Ghosts??? Freaking out!!

My newborn is always looking over my shoulder or above me. She starts laughing or babbling each time. The other day I went to check on her while I thought she was napping but she was wide awake smiling and babbling. I swear it freaked me out because I said "What are u smiling at baby girl" I kid u not she slow motioned her head towards me and just started staring at me with a semi grin. Does anyone else have similar experiences? My hubby's mom passed away and he believes it's her!