I just noticed today that my exhaust was popping or sounding like it was missing or backfiring quietly today. I didn't even notice it with the radio on just happened to turn it off to talk to a customer on the phone. Almost sounded like my truck when I go over little holes in the road. Like just quiet road noise. Rolled my window down sitting in the drive through and it would just makes a soft "burb" sound maybe once or twice a min or so. My truck didnt flutter in rpms and everything seemed to be running fine and no smoke came out of the exhaust during each time it would do it. I would hear it in park and driving at slower speeds. Couldn't hear anything at faster speeds due to road noise etc. Kinda weird though. Any suggestions? I changed the fuel filters about 7k ago. Popped the hood and it idles fine and everything. Dont know if I'm looking too deep into it or not but it has never done this before.