I guess that doesn't surprise me since humans have floating ribs as well...I had never noticed that on Toki though (I just tried to feel it on her and she was like "what the heck are you doing?" lol)
Your post reminds me of when I took Toki to the vet and asked what this hard white growth from her gums was (we had her baby teeth removed and then a few months later I noticed some white lump near one of her upper canines and thought maybe she got something lodged there that she was chewing on). My vet was like, um, that's a tooth (*facepalm*) lol. I thought all of her adult teeth were in so how was I supposed to know more were still on the way??? haha It's still good to hear from the vet that things are fine though!
I think a lot of us are just hyper-vigilant (I know I am!) about making sure that absolutely nothing is wrong with our babies and that everything is normal...it's always better to go ahead and ask anyway though