Donuts on a Rope...

Early the other day I was walking outside to get the mail when I looked up and saw a jet stream. Not an uncommon occurence as many aircraft pass over the area on the way to bigger places with bigger plans. But after I got the mail and was looking back up I saw that the water vapor had clumped up into little balls, each connected. It looked peculiarly like some donuts-on-a-rope so often coincided with the Aurora Hypersonic Jet (Or at least a PDE)

Do the donuts form on the rope instantaneously or wait for a few minutes for the cloud to disperse to become obvious? For those that are wondering the trail was going NW or SE (couldn't tell which) and the aircraft was out of sight. Any knowledge on if this was the actual phenomenon or just a roll-of-the-dice coincidence?