Is this normal at 4.5 months?!

[Cgow]

Hi all, so I have a beautiful, happy and loving baby girl who is always smiling (with the occasional moan when she's hungry... Obviously!) she sleeps through the night without a peep for 12 hours solid.. She is a total pleasure! but recently she has become different around other people.. Very selective she cries constantly around her grandparents in particular.. This is mine and my partners. Now I don't know what to do as the crying gets so bad they can't comfort her or calm her down, she will refuse to eat in there company... With my dad if she even catches a glance of him walking by or in the room it's enough to set her off.
This has only happened in the last month I would say she was fine with them all before this point.
It's just upsetting as I do sometimes get embarrassed of her behaviour .. Which j shouldn't do I know. Is this normal for them
To do this.. Just loose interest in people completely and are there any parents that have been through this that have any tips to help ease it?
I will add my partners dad is very grumpy and could take the life and soul out of a room with one look.. Sounds horrible buts it's true .. His mum is very over the top excited and happy.. And my dad wears glasses. I have kind of Idebtified these as possible issues as funny as it sounds!
Thanks all x

[sproketmx]

Some kids can just be like that. My first girl was like that. If she woke up and someone apart from me was holding her hell mend your ear drums. She's fine now though and nearly 5

[Cgow]

Sounds like my one, she's generally very happy.. But then she sees her grandad and the tears start flowing and the screaming gets louder.. This will go on for ages! I think I might just have to put it down to the fact she does not like them and stop feeling guilty about it lol x

[skankingpiglet]

Mine started this around the same age with any men except DH and DH's Nephew (who looks like the spitting image of DH). It gradually subsided, but she was around 8mo when she stopped it with DstepF I think it's because he's quite loud (in a friendly way) that it took so long with him.
Just gently persevere, I think they just need to get used to these other people who as a newborn they weren't really aware were any different from mum and dad. How often does she see them?