I acquired my 2006 Hurricane (also a Thor product) used in 2011 and pretty much all the roof seals had degraded and needed attention. Six hours of labor is about right but the labor rate at potentially $150 an hours is a bit high even for CA. You could certainly add additional sealant if you don't mind the "bigger the glob the better the job" look.
Removing old and resealing isn't difficult and there are Youtube videos which will help show a few tricks to make the job a bit easier. Lot easier then sealing a bathroom shower considering it doesn't have to look perfect just has to be weather tight. If you plan to attempt two words of caution NO RTV. Don't ask why not since this post is already getting long just NO.
I'm also a fan of Eternabond tape. The stuff is expensive at getting close to $1 a foot but once installed the tape will probably out last everything under it.