http://www.ice.gov/sevis/travel/faq_f6.htm
see 6B. you'll learn if you have to got any annotation about OPT for F2 I-20. My answer is NO. you should've submitted F1's I-20 forms, if any, for your 485. Consult both your school and a lawyer, becasue lawyer may tend to make fuss of it. and let's know the final answer. but i'd say not be too worried.