Baby fiddling Ear / Scalp

Im not sure how to describe but my 4.5 month old baby recently started to fiddle his hair/scalp right above the ear. It's like he is kind of scratching the spot. Only does on right side of head. No signs of irritability / distress and also no visible rashes. Is it normal? Went to google and results say might be ear infection / discovering got ears / teething but I'm not sure Edit: thank you everyone! It seems like sleepy cue / possible teething after reading your suggestions and trying to look out for patterns :)