I agree with the posts above, but I would also suggest you do a search for some of the threads about caulking the shower enclosure. I only say this because I always err on the side of caulking the living daylights out of stuff but there is some good advice out there about what to caulk and what not to. Some of it seems counterintuitive until you pause and give some thought.
Not saying this is or isn't a place that should be well-caulked, just saying do a little research first to make sure you aren't inadvertently creating a future problem.
Good luck.