i think it all depends on who you get there. i suggest you go back, tell them it goes 25, has less than 1.5 hp, and see what happens.
when i registered my honda express in boston, they said 'you know you can only ride this on dirt roads, right?'
i said, um yeah, then thought about all of the dirt roads in and around boston (there aren't any) and got my registration. of course i ride around on the street all the time and no cop has ever said anything. it is totally legal to ride in the street here, and the dmv lady just didn't know what she was talking about.
so i guess my point is that they just don't know, so if you act like you know, then you're ok.