Ceallach, if you can stand having a loved one being missing for several hours, and not contactable, without imagining a million different horror situations - well, I'd love to have your steady nerves, because I can't make myself do that! My mind will insist on making me miserable with all sorts of terrors.
If we assume "several hours" is three or more (say, he was supposed to be home at 6, and it's now 9 pm), this would sound like more than traffic to me. And the prevalence of cellphones these days makes being out of contact even worse, because we're so used to being able to check on our loved ones whenever we want. Yes, there are plenty of scenarios that could cause someone to be this late that do not involve death or mayhem - but also a number which do. I think mocking someone who is really worried about a situation like this is cruel, and therefore rude. Giving reassurance that all is likely well is one thing - treating it like a big joke is another.