Icon Flashing on Notification Bar.

This has happened three or four times recently. A little green icon will flash in the top left of my screen in the notification bar. It pops up and then disappears. It looks like the green Android figure but it disappears so quickly that I can't get a good look at it.

Has this happened to anyone else or do you know what it means?
Thanks.

By the way, this is happening on my Samsung tab. Model SM-T320. I probably didn't post this in the right category but I'm new to the forum. Sorry.