Breaking a too-long radio silence born of work stress…
Anyhow, leading indicator: SMSes in the office.  Intra-office SMSing.  Why?  You may step away from your computer, but you always have your phone with you.
(Other contributory factors: European coworkers, large enough office to make running all over looking for someone a drag, smartphones assigned to all senior managers.  But give it five three years, you’ll be doing it too.)