Do all spiders smell of fuel?

[NSFIAT]

I've been facing the same issue with an '81. I pulled the tank last year due to heavy rust on the interior and have been replacing fuel lines, etc before the driving season. I checked the check valve today and noticed the same grey coloured grease - it had even started to build up on either side of the vapour lines. Is this common? Or something I should be worried about? I've cleaned it out and the check valve seems to be working properly.