when my 13mo daughter is in her high chair she starts to pull on her bib and stare at it, this only happens when she’s in her high chair or sometimes when she’s sat in the shopping trolley. If she doesn’t have a bib on she will use her clothes or just hold her hands up and stare at them, if I disturb her she sometimes cries? I try to distract her before she starts to do it and 95% of the time if she does do it I can get her to snap out of it but then she sometimes goes back to doing it again 
I’ve asked the health visitor but she doesn’t seem to understand what I’m on about 🤦🏼♀️
I’m hoping it’s just a habit she has, as it’s only in her high chair or trolley that she does it.