Don't think I've heard it or read it before, but I knew what it meant. It uses productive morphological derivational processes to coin a new word.

Aside: it's interesting how -ster has gone from the native Saxon feminine agentive suffix to a masculine one (under Anglo-Norman influence -teur/-teuse fr. Latin -tor), and lately a pejorative one. (cf. job-related English surnames Webster, Brewster, Baxter, Dempster, (but seemstress); and gangster, ?youngster, (perhaps with influence from non-related Latinate pejorative suffix, e.g., poetaster, oleaster.)

Ceci n'est pas un seing.