If it were me, I'd double check. But I'm not very trusting...

 

Sadly I am not either and will still check it this week.

 

This is where I originally saw the issue and fix.
I hate to say it, but I have to believe the dealers are well aware of this and figure if they clean the breather, it saves a ton of time and maybe once the pressure is relieved, the seal will once again do it's job....maybe. So I would check the cap to see if they took this approach, then clean everything thoroughly so I can look in the future to see if it continues to leak. If it does, they tried the easy route first. Can't say as I would blame them for trying that first, I just don't believe they should claim they replaced the seal if they didn't. A little honesty goes a long way with me.