We have a 7 month old puppy. The last week or so he has taken to chewing on the skirting boards, the TV cabinet, the coffee table legs and my bedside shelf. He does it only in the morning and evenings and we are there in the room with him. He isn't left alone all day, gets plenty of exercise, has chew toys gallore (he buries pigs ears rather than chewing them). He sort of lies down up close to the item and then sneakily gnaws on it until one of us catches him and tells him off.
Any ideas why?