You need to download, complete, and submit an "in-School Deferment Request" from Great Lakes - do not depend upon your grad school to make sure your status is up to date. If you take the time to READ your promissory note, you will find that you are entitled to in-school deferments as long as you attend school at least 1/2 time, and not a credit less. You will also find that you are entitled to ONE 6 month grace period - so while you are currently using up your grace period, once you fall below 1/2 time enrollment, your loan payments start up again. If you take the time to read your promissory note you will also find that there are other deferments you might wish to use in the future, as well as a couple of repayment plans, forbearance allowances, and cancellation options.
One MIGHT hope that someone enrolling in Grad School has the foresight to read what you are signing - especially where there is money involved!!