Either a bad day (or stressful bad 'time') causing this 'look'.
But more than likely one of two things:
1) Drugs -- He's had problems before, and this is a possibility. Though opiates generally aren't going to cause what you describe. Yes, they can cause a general 'stare' or glazed over look -- but the eyes would be far from 'WIDE' .. So I think you can rule out opiates specifically. Now other types of drugs could contribute -- maybe stimulants of some sort -- (Anything from Methamphetamine, regular Amphetamine salts, etc..)
2) He isn't getting any younger. While he isn't *old* by any means.. he is aging just like everyone who is over the age of 18.. (Yeah we start to age about 18 yrs old.. ) -- So maybe , with his limelight lifestyle and money, etc -- he had a face lift (or maybe just the eyes, or brow done) -- When it looks like a constantly 'surprised' person.. deer caught in headlights.. etc -- This is usually the case. Also this usually happens when the 'patient' insists on a less than recommended *natural* look and go for a fairly abrupt change.
Could it be from not taking drugs -- mmm.. Technically, theoretically, yes. Though I really, really doubt it.