A big financial payoff is due to you, but it might take a bit longer to get it than you had hoped. You don't necessarily have to get up in anyone's face about what they owe you, but you should make some noise. Send them an email reminding them of the balance due: a phone call might seem friendlier, but communication about stuff like this should be conducted in writing. Plus, writing it out will give you the chance to word it a way that is diplomatic yet firm.