Bean was so used to either tricking Fuzzy into giving up his tummy treat, or protecting his own vitamin C treat from Fuzzy and Potato, that he would carefully guard his vitamin C treat from Grizzly. He didn't realize we would be giving them to Grizzly as well, to help him recover from whatever health issues he might have picked up a the pet shop.
Grizzly is too polite to steal anything from Bean anyway. Except hugs.