Before reading the spoiler I was ready to call/jam. My reasoning is that the CO is a station and since you picked that up the Button probably did too. They might have the same feeling about the call that you do and they're out of position in this case because you get to act last. They could be calling hoping you fold so they can go heads up with the calling station. I wouldn't discount AK or AQ to be in the buttons ranges pre flop but I also think those ranges raise your 400 to begin with. With the second nut draw and ace solid kicker I'd figure I was either at parity or slightly behind but drawing ahead of the other two and would have called here. If not a call a jam and if a call I'd call under the assumption that I'm basically all in on the next street looking for a club. I also think your fold was super reasonable and well-disciplined because like you said, since you believe that you have the skill advantage, you might end up getting a better spot later to get your chips in.
