Do we need to contact the trustee about our tax return ?

Yes, and you should also amend your petition to reflect the additional asset, if you have not done so already.

In many states, your tax refund is NOT a PROTECTED or EXEMPT ASSET, so your Trustee is able to take the refund check & use it to pay your creditors a portion of the money you owed. Amend your schedules & see if the refund is exempt first, and if it is not, be sure to promptly give your Trustee the refund check. Of course, whether or not the refund is exempt, you must give your Trustee a copy of the return paperwork

You could have exempted your anticipated or estimated refund when you filed for bankruptcy assuming you had enough wildcard exemption to cover the refund. At this point I would just take a copy of the federal return and mail it to the trustee with a letter explaining that you will be receiving the refund and asking if you should amend Schedules B to report the asset and C to exempt the refund. If you have enough exemption available the trustee might not care if you amend the schedules. On the other hand if your refund cannot be exempted then the trustee will claim it for your unsecured creditors. Although technically you should amend the schedules B and C the amount of the refund and the available exemptions dictate what should be done. For example if it is a few hundred dollars and you have plenty of exemption available then just sending the tax return to the trustee should be enough. It is strange that you have not received your discharge since filing in May 2010. There might be complications in your case and if so you should contact an attorney to evaluate the situation.