That is unusual. Odd things can happen with a first check from a company (I had one send my first payment to a person with the same name in another part of the country who shopped for them in the past and another company send a first check to a wrong address they had entered in their system erroneously), but since you have received one check at least, one has to assume that any goofs like that have been cleaned up already. With a little more than a week left before 30 days has elapsed, I would probably wait and when I called them again ask that they double check your mailing information since this is two months in a row that there is an issue. Meanwhile you may want to check your profile to make certain for yourself that everything there is accurate.
My interactions with them have all been highly professional and there never has felt like there was any shadiness or wink wink involved. My sense is that they are a financially sound company with no reason to 'rob Peter to pay Paul'. So my reaction is there is a slip up here that both they and you would want to have rectified.