OPT EAD and I-485 application gap question

[axingdi]

Hi there, we received a I-485 RFE, one of the items is need to validate we maintained our nonimmigrant status in US since last entry. My wife had a problem, she applied her F1-OPT and I-485 almost at the same time, because she graduated in December, I already filed my I-485 at that time, so we file her F1-OPT first, then after a couple of days, we submitted her I-485 application (Her I-485 application is a few months after my application). Both of the two EAD cards were approved finally. But now we wonder if there is a problem these two applications were filled too near to each other. Does I-485 application have to be 90 days after OPT as someone said? What is your suggestion for us to submit her RFE documents regarding her maintain status part? Thank you!