No, there is no affirmative obligation to disclose this information--that's for the buyer to determine, if he/she is looking for a Freddie/Fannie loan (or more generally, during the process of applying for a loan, if he/she needs one). Just make sure to not even imply that it is approved: while you don't need to disclose it, you also can't misrepresent the situation. Say nothing about this issue at all.