Somebody put a rubber band around them when the were smaller. lol

It is usually referred to as "zippering" and is a physiological response related to pronounced fluctuations in air temps at pollination time and during early fruit development. Most of the time zippering of fruit runs vertically but it turns up like this on paste types sometimes because of the long shape of the fruit.

Not really much you can do to prevent it but most of the fruit is still edible.

Dave

This post was edited by digdirt on Wed, Oct 16, 13 at 11:24

Thanks, Dave!