You are fine. You still showed the dedication and caring. It doesnt matter that they shut down, will not hurt you in any way as long as some record does exist in case somebody wants to look it up.
Can you try to contact your former volunteer coordinator there? That way, if anyone ever raises the issue, you'll at least be able to offer his/her current address.
I wouldn't worry about it, however--it's common for organizations (profit or non-) to "vanish" through absorption into a larger system, a name change, or (sadly) a failure to thrive.