the icon on the right side (its a stopwatch icon) indicates time left for a snapchap to be visible to the viewer. If I were the one ending a snap, I can set the time limit anywhere from 1 second to 10 seconds before it disappears off of the viewers screen forever. There is one other option - i can set it to be viewable with no limit. This means my friends or whoever i am sending it to can view it again and again until it's no longer available. I don't know if this option was available in Feb 2017.
I cant tell what Libby had it set to but the icon is an indication it was set for a time limit and the time is running out.
This is actually about Androids but Mr Hickman is working to crack the code on iPhones.
"But apparently Snapchat doesn't actually delete the photos. It just buries them deep inside a device.* A digital forensics examiner named Richard Hickman has found a way to resurface the private pictures on Androids. The finding is similar to a flaw Buzzfeed uncovered in December."
BBM
Actually, Snapchat Doesn't Delete Your Private Pictures And Someone Found A Way To Resurface Them