Found a threat... but nothing is in the threat box

Hey, i had a weird experience and was wondering if anybody else got this before.

 

i just saw a threat found box pop up... except it was empty. Usually there would be something in the box that i could click and open a web page about.

 

So is this just a glitch?  It came up right after i ran a fullscreen program, so was it just a false alarm on that program?

 

Any help or suggestions would be appreciated