If it's not normal and you don't know what it is, it doesn't hurt to get it checked out. I have a 16-18 year old bourke parakeet with cancer on her right foot. She had laser surgery to remove the mass, although I wanted to have her foot amputated instead. Vet didn't feel it was necessary, although at the time we didn't know it was cancerous (took a sample and came back fine). Two years later and it's grown back, and then some.
Image before surgery
After she had the mass removed and the bandage. There was still some gauze left on her foot that fell off shortly after...
I think this one was taken a year or so after surgery
And a somewhat more recent image...
She was 14-16 years old when she went through surgery, and I cannot put her through that kind of stress again. I was afraid she wasn't going to make it through the night. As it stands, she's past her expected lifespan and her health seems to be deteriorating slowly due to age.
First night after surgery...
I'm not saying that your quaker has cancer, as I would doubt that. I would lean more towards an injury or the circulation to the toe getting cut off than anything else at the moment.... but when in doubt, it doesn't hurt to find out.