Blue dots appearing on outbound call screen

For the past few months, blue dots have been appearing on my screen when I make outbound calls. I'm on an iPhone SE running iOS 10.1.1. I just had the phone replaced for an unrelated issue, and the blue dot phenomenon seems to have ported in with my backup. It started with one dot, and gradually increased. Today I took screen shots with 6 and 7 dots. Two screen shots attached. Is this happening to anyone else? It's not interfering with functionality - it's just kind of weird.