Glad your pigs enjoy the dried herbs and having fun re-decorating their cage. My cage is an utter mess as to encourage my senior pig (who also has arthritis) to eat more hay, I have a pile under her stool so she can nibble. Of course the hay bits then gets everywhere around the cage and caught on the fleece.
I also buy the dried herbs from Burgess as a treat and sprinkle that in their hay. However, as it contains a lot of high calcium herbs, I feed it quite sparingly as a treat.