jason's surname/ethnicity

So I don't have to go through every single episode again to find out, can anyone remember if Jason's surname (Penopolis) was ever mentioned before the final episode (he says it when introducing his ending)? In the penultimate episode, Definite Possible Murder, Jason says as an aside during a conversation that he's Greek, but the bit where he does kind of sounds like improv by Jon Benjamin. I was wondering whether or not Jon ad-libbed this and so they added Penopolis as Jason's surname in the next episode accordingly. Otherwise, Jon Benjamin would have to be remembering some fairly trivial, nerdy, rarely mentioned detail from the past about his character, which - with all due respect to Jon - I dont think is very likely....