Well that's just friggin' adorable..lol.
At 7 weeks old this could simply be a very young, non-weaned baby doing the "baby wing thing", especially if this was during feeding-time...However, as already mentioned, drooping-wings can be indicative of a lot of different health issues as well.
I would absolutely request that the breeder take the baby to a Certified Avian Vet (only, no general vets or non-avian specialists), and that you are guaranteed a health-certificate along with the bird, and some kind of health-guarantee with the bird. If a breeder is unwilling to do this, then you need to be suspicious.
When are you supposed to be bringing this baby home? Has the breeder given you any updates on how the weaning-process is going? The reason i'm asking is because I'm going to assume that this is just a very young baby being a baby, that hasn't fledged yet or is in the middle of fledging right now...That being said, he doesn't look like he's at all ready to fully-wean yet, so you want to make sure that the breeder isn't planning on sending him home with you until he is fully Abundance-Weaned. The last thing you want to do is to bring home a baby bird that isn't fully Abundance-Weaned and have to give it hand-feeding of formula...