It's fairly common to see "tied" notes in classic banjo pieces; often it is specifically stated to let notes ring out and sustain while you play other little figures. The Washington Post March is an example; there are many others.
All I'm sayin' is, Who you tryin' to kid? Sustain on a banjo has the half-life of a nano-second. Especially when you go off and play other things during the presumed sustain period. You can push down on that note for all you're worth, but it still ain't gonna last long.
Sorry if this sounds like a rant. I have encountered this on several pieces lately. How do classic banjoists handle the sustain issue?