This is known as a leap second, named after Usain Bolt leaping over the finish line a second faster than everybody else

Never in the history of time has a minute contained only 59 seconds. Even in Africa. And it has been decided that from 2035 onwards, we need to alter time itself in order to eradicate this irregular minute.

We can only hope that before that time, we get to experience one of these magical short minutes. It may happen yet.

Savages

If we're including time dilation in this, so does velocity. This means that the velocity from earth's rotation that you gain with elevation counteracts the loss in gravity to some extent (I don't know what the total is, I can't be fucked doing the maths). It also means that latitude effects time dilation because the equator is moving faster. This means that 60 seconds in south Africa is not exactly the same as a minute at the equator.