[Roadster]

IMO, I don't think it is a major issue. Follow the advice above, checking your drain tube. To me it may be more of a moisture issue, is the cap always completely tight? If you are concerned, I would change out the fuel filter and then cut open the one you just replaced. That way you would be able to see if there are any particles that were in the tank and caught in the filter. And when changing the filter, if the fuel is that bad, mostly likely you would see a dis colorization and particles come out from the tank line to the filter.