I have not seen that - it's pretty clear you must be on the standard 10-year plan, or an income-driven plan. In fact, I've seen countless people see what they thought were qualifying payments NOT count because they were on graduated plans.
I wonder if it's because they hadn't yet started paying an amount in excess of the "regular" 10 year monthly payment. It takes awhile to get there. I think I crossed that threshold in year 8, which would be 2008. So I *may* have made 9 years of qualifying payments.
This fact sheet says (pg 2):https://studentaid.ed.gov/sa/sites/default/files/public-service-loan-forgiveness.pdf
"Any other Direct Loan Program repayment plan; but only payments that are at least equal to the monthly payment amount that would have been required under the 10-year Standard Repayment Plan
may be counted toward the required 120 payments."
And this one (pg 4) says: https://studentaid.ed.gov/sa/sites/default/files/public-service-loan-forgiveness-common-questions.pdf
"15.What other Direct Loan repayment plans would give me a monthly payment that is at least equal to the payment that would be required under a 10-Year Standard Repayment Plan?
Under the Graduated Repayment Plan, payments start out lower and then gradually increase, generally every two years. Therefore, payments made during the later portion of the repayment period under the Graduated Repayment Plan may in some cases equal or exceed the payment amount that would be required under a 10-Year Standard Repayment Plan, and these payments would count for PSLF."
Since I'm not sure which loan amount they are using - Feb 2000 start or Oct 1 2007, I'm not sure what they will calculate as the 10 year standard monthly payment. And since they switched my servicer, I don't have my loan amount remaining in 2007. And even using my 2000 loan start, the interest rate switched mid-loan, so calculating the amortization on a 20 graduated repayment has been messy.