Iphone 7+ speakers make a crackling sound

I got the iPhone 5 days ago, and this happened twice today, as I was dialing my girlfriend on FaceTime, the speakers began to make a weird crackling sound along with the dialing sound. It then happened again about 4 hours later. Both times I was having connection issues so I don't know if it's because of that. It has not happened since and I have not been able to replicate it at all.

I'm contemplating going to my carrier store and exchanging it, and I also plan on going to a genius to see what they have to say, I'm hoping it's not a hardware issue and it's just iOS 10 acting weird. What do you guys think? I also did some research and apparently this has happened to earlier iterations of the iPhone. Thank you guys!