This is about my '23 Freewheeler. Took a 40 mile ride to lunch today. Nothing special, not too hot, no traffic jams. Most of the ride was 55mph and above. Was idling at a traffic light briefly when the exhaust sound changed. Not sure how to describe it. Not a repetitive bang, but that's the closest I can come up with. A slight rev of the motor and it stopped. Nothing unusual while riding. Did it again on the way home and in my garage when I got home. I let it do it for a bit while I checked things. The motor seemed to be vibrating more than usual so I started checking bolts. Nothing loose. While looking around I found a bolt hole on the front manifold mount with no bolt in it. The back head has a bolt in place, but no washer. Can this be causing me a problem?