... that would be when, sitting in the departure lounge at the airport, you get an email from your cousin saying that your father (who you last saw three hours previously, with your mother - both apparently healthy at the time) is Trying to Contact You. Of course, I went still, and cold, and tactics started running through my head (can they get my bag off the plane? can they courier it - well, somewhere - whilst I dash to whatever hospital ...). And I took five deep, slow, breaths, and called him.
He wanted to know if I happened to have the password for his modem.
And yes - this was LHR Terminal 5's first class lounge - though I assure you I was flying standard cattle class - all the same, a perk of a lot of flying last year.
And yes - because I am Boy Scoutishly Always Prepared, I did have my parents' modem password. Arrrgggghhhhhhh.