Credit cards after bankruptcy
After filing bankrupcty recently, I remembered a couple of retail credit accounts that are completely paid off and in good standing with their respective stores. Being that they were paid off, and I had no outstanding debt with them, they were easily missed when I reported all the rest of my debt and credit cards to my trustee. My question is, what becomes of accounts like this after my discharge? I realize I can’t use them during bankruptcy, but am I legally okay to use them after discharge? Must I inform them I am in bankruptcy or discharged?

You were legally required to surrender ALL of your credit cards to your trustee when you filed bankruptcy – even for the accounts that had zero balances. The trustee would have returned the cards to the lender(s) and then the lender(s) may decide for themselves whether or not to extend you credit in the future.
By not surrendering these cards to your trustee your are effectively “hiding” the fact that you filed bankruptcy from these lenders – potentially you could be getting yourself into trouble if you use these accounts in the future and the lenders find out about your bankruptcy.
I suggest you “come clean” and surrender the cards to your trustee so they may be dealt with in the appropriate manner.