What do I do if my new guinea pig gets scared (and starts squealing very loudly?)

[fluff.]

this happened yesterday, but i still would like to know
sorry for any incorrect grammar along the way

so, like, i got my new guinea pig 2 days ago, set her in a temporary cage to quarantine her for a week, and later picked her up with my other guinea pig, placed them in the playpen, and set toys and other things in the playpen. the two remain completely still for a while, but when my older female came in her hide and sniffed my younger guinea pig, she (my younger one) squealed in a very high pitch tone. i researched it and found out she was scared, but the oldest didn't bite her or do anything for that matter. how long does the "scared" sort of "mood" last? or is this a traumatizing thing? i'm not super super experienced with guinea pigs, i know quite a lot but i was still worried.

 

[Piggies&buns]

A high pitched squeal in a bonding situation is likely to be submission squealing. Submission squealing one piggy saying to the other I am not a threat to you.

It takes two weeks after the neutral territory introduction for them fully establish a relationship and hierarchy and that during that time you continue to see such behaviours while they sort out the details of their relationship

The guide below explains how to carry out a bonding and the behaviours you are looking for.

Bonding and Interaction: Illustrated social behaviours and bonding dynamics
Sows: Behaviour and female health problems (including ovarian cysts)

Do note that quarantine should not be carried out for piggies who are under four months of age - their social needs and companionship are so important that you carry out a bonding on the day you bring the piggy home. Also, that the correct length of quarantine for piggies over four months of age is two weeks in a separate room