Our 6 month old beagle, Squeegee, has just recently started barking at the front door. We rarely have visitors but live in a townhouse and he hears the neighbors coming and going. We've had him for almost 5 months and he never did this before. Perhaps it's just part of him getting older? I don't want him to be one of those dogs who goes crazy at the door. Any tips for getting him to stop that?