This has happened twice this week. I turned on an iHeart station which is heard on AM radio in Wisconsin but can be heard anywhere using iHeart or another streaming site.
Even though the station runs ads, I heard a commercial for Westwood One (which happens to supply the music on the radio station). It seemed to be running at the wrong time and the next song started in the middle. Since it happened again today, and because the commercial started exactly when I started listening, it's clear they're doing this.
Even weirder, one of the commercials on the radio station was for a business in my area. It does not operate in Wisconsin where the AM station is. The ad specifically mentions gas station points which can be used at the grocery store chain (where the stores have gas pumps, which is not the case at either of the stores in the chain that I go to) or at BP.