Call your dealer and schedule your repair, the parts are available. Do not wait for the second notice, it may never come.
I am scheduled Oct 6th for repair.

And as posted by TNtech (Thanks!), test your horn before you leave the dealership, the horn buttons inside may be broken during the repair. I plan on shooting a quick video showing my working horn right before they get my truck. Just a little insurance...

 

Any recall I've ever had came with a second notice for the part. I'm waiting for the part notice right now too.

 

Call your dealer if you want to get it done, the parts are available.

Mine was taken care of in October, no second notice as of yet.