Received this note stuck to my front door today from "Department of Homeland Security United States Secret Service"

Today I heard someone knock on my front door about 2PM, but I couldn't answer as I was stuck in a meeting. I checked my security camera and saw two gentlemen at the door about 30-50yr old id guess (I figured they were selling some kind of home improvement service like new windows, etc... About two hours after they left I went outside for something and found this note from "United States Secret Service" hanging on my doorknob asking me to call a number to talk to an agent about a twitter account that apparently "posted a threat towards the president back in November".

This is a scam right?