My dd sees her grandparents about once a month on average. They're both quite old and my mum has dementia and my dad is a bit of an old codger and not the world's most child-friendly person but they love her and make this clear. She barely talks when they are there (can't shut her up normally) and is reserved to the point of being hostile with them about half the time she's with them, won't let them hug or hold her at all and frequently walks out of rooms when they walk in.
I'm not worried in a sinister way, i.e. don't think either of them has been cruel to her or anything like this. I just wonder if its normal for a child who has met its grandparents on numerous occasions to be so uncomfortable around them. I'd expect her to be more comfortable with them by now. She isn't the most extrovert of children but she's pretty sociable at nursery with the childminders and the other kids. She's an only as well if that's relevant.
Am I over-thinking this or is this a sign that there could be some behavioural issues?