You pay an adoption fee to a rescue organization but you do not buy or purchase pets from them so the rules and expectations aren't the same as purchasing. It could be normal. Also could be something like growth plates or luxating patellas or hips or numerous other things. It's hard to say without more information and you should have it checked out by your vet regardless in case it is a problem. Good Luck.
Why Is My Dog Bow Legged? We Bought Her From The ASPCA...She's Walking Weird..Is This Normal? What Should I Do About This?
I would contact the ASPCA and asked them but you should have you dog checked by your vet right after you get it to have a check up done. Some dogs are this way like bull dogs ect. So I would contact the ASPCA to talk to them first.