You are correct in your thinking of three payments. There is no way to know if a payment was missed or not because there was no publicly announced payment schedule.
Directly from the settlement announcement:
Additionally, HTI will pay an undisclosed cash settlement in three payments, with the final payment concluding on March 31, 2013.
Now, if it were three equal payments, then each payment would be about $367k. Today's PR says $700k paid which is pretty close to two payments at $367k each. My question is in line with yours, was a payment missed and then they made up for it or were the payment terms such that required a large initial payment and then two smaller payments (which doesn't make much sense)?