White or grey dot that pops up on the top left corner sometimes

Every now and then, a grey dot shows up on the top left corner of my kindle. Sometimes, when I go onto another app/game, it disappears exactly when I go onto it. Also, there is no notification related to the dot when I swipe down on the screen. Does anyone know what this is?

EDIT: When I decided to turn off Silk Browser notifications 5 minutes ago, the dot disappeared right when I pressed it. I assume it's over now.