[cypher]

It's not unusual to see behavioural changes after you've been away, it's only been a few days so I would think he will settle down again soon enough, try to ignore the bar chewing as much as you can & only pay attention when it stops to help prevent it becoming an attention seeking habit.
If you don't already scatter feed rather than using a bowl & hide some of his food & treats in little cardboard parcels or toilet roll treat toys so he has to work to find it, that may help distract him. Does he have whimzees to chew on? If not that's another thing that might help.