Spots on Holly leaves
 

A few weeks ago I purchased online a number of different Holly plants for a mixed holly hedge, they were all healthy when they arrived, but I have just noticed spots on all the leaves of one of the plants (Handsworth new silver), is this a disease or something I should be concerned about? Should I remove this plant from the hedge to prevent spread to the other hollies? All the other holly plants are still healthy including those of the same variety. Thanks