Older dogs develop quirks, it doesn't necessarily mean that is a sign of her time. It could be behavioral, mental (kind of like old dog dementia) or a physical symptom of illness. Mine is 11 and she also licks the carpet. She usually starts by licking her paws, then she likes to go and lick the carpet where she is laying. She is definitely a mental case, I think it is just a soothing activity for her.
I read this article the other day about why old dogs are the best dogs, it's so sweet: