Do I Need to Worry About Diesel Fumes ?
If you can smell them, then YES!
Every fuel system needs to be completely sealed in a boat. Here is an MSDS on diesel fuel: http://www.wilshar.com/Forms/Diesel%20Fuel%20MSDS.pdf
And as and ex-fuel site administrator I can tell you that any
fumes in an enclosed space is not good. Gasoline fumes are a killer.
So, if you can not
smell the fuel then no worries, but if so, you need to do a clean up and seal.