Missing tunnel rivets by design??

[PAvector]

Under the gas tank on the left front side of the tunnel is one rivet, the other side has two. Why? My single rivet is loose. Can I add a second one or is there some clearance/design issue preventing this?

 

[cannondale27]

I noticed that too. Must be by design. All those tunnel support rivets are loose on mine every year it seems.