Why is it ?

Because Time never stops.

Maybe they forgot what the time was.

to make sure that they are ABSOLUTELY TO THE SECOND!

Short-term memory loss perhaps.

because they were looking at their watch for another reason, not for the time. Boredm, embarrasment etc We all do it!

It's the behavior of homo-sapiens. Try readin H. Russell's Anthropology

Do you want a serious answer? I would venture a guess that it's because when you look at watch, you get an impression of the time that is not based on language. You just intuitively understand "hand on the six" means that it's time for your meeting. You don't always stare at your watch long enough to say...ie..."seven thirty-two."

When you ask someone what time it is, they have to formulate a verbal response, which probably requires different neural circuits. So they look again, because it feels more natural and buys them some time while they translate their non-linguistic impression of the time into words.

Double checking to give you the proper answer I guess!

Because when they look at their watch the first time they aren't really looking to see the time. They are looking to see how much time they have for something, will they be late for the appointment, how long until....

good question.