Jeff,

I've been doing for the past 25 years what you've been doing & have yet to have a problem. I have noticed at times some slight discolouration of the fuel that remains in the tank - this seems to be from carbon flecks that come via the muffler pressure line. But one thing I do however, is ALWAYS filter the fuel as I pump it back into my fuel can & filter it again when refilling the tank for each flying session.