Should be pretty easy to check and re-caulk if found necessary.
I just put a new plastic vent on ours recently because the old one was damaged - if I recall, it just went on with butyl tape behind it - no leaks so far. If you found what looked like an entry point for a leak, caulking with Sikkaflex or Acry-R should do the trick. Maybe try spraying water on it?
On the other hand leaks can be deceptive. What else is close to being in line with the leak? AC unit? Fantastic fan? could also be the source.
Brian & Connie Mitchell
2005 Classic 30'
Hensley Arrow / Centramatics
2008 GMC Sierra SLT 2500HD,4x4,Crew Cab, Diesel, Leer cap.