Vapor return or liquid return line?

The fuel "vapor" filters have a small bleed hole so vapor can escape but if there is no vapor a small amount of fuel will be escape there.

If you can find a ethanol free gas supplier near you, run your tank down to as close to empty as you feel safe and then fill full with ethanol free, and see if your issue goes away with all the lines and filter as it was before the filter change.

Pure-gas.org