I had just been browsing a web site (Snopes.com) on my phone, when my phone rang.. After the phone call ended, I started to hear some kind of ads through my audio speaker. I don't recall what the first ad was, but the second ad was a Verizon ad. A third ad started, and I couldn't tell why it was playing or what app initiated it. I went back into Chrome to see if there was video playing but there wasn't. Youtube wasn't running in the background.. I eventually shut the phone and since then the ads have not played. I ran a Malware scan on the phone tonight and it came back clean.
Why would an audio ad play randomly on my phone?