The 'laboured legs' could be cause for concern, I think. When she walks, does she seem off balance? Does one wing lie out in an odd way?
There are quite a few nasty viruses that can affect young birds, including Mareks Disease.which is very common in home- bred chicks, and one that more commercially orientated growers always vaccinate against. Dud you notice anything wrong with her when still at your friends house? If she were mine I would get a vets opinion, because if it is Mareks she will need to be PTS. it's not curable and she will go on shedding dander with viruses in, which will infect the others. Not saying this is the case, but you do need to have this in mind, I'm afraid.
They do start moulting their chick feathers usually around 12-15 weeks and then they grow their first lot of adult plumage which lasts them for up to 18 months, until their first proper adult moult. Moving home always stresses poultry and this frequently triggers health problems, I'm afraid.