Just in case someone else has the same issue, I've figured it out. In richfaces 4, 'bottom-right' positioning is no longer valid. You have to use 'bottomRight'. I am completely shocked that none of these changes have made it to their online documentation. I have wasted time trying to figure out what was happening with this component. I cannot believe users are expected to go to the API JavaDocs and look through each class for possible attribute values.
If any RichFaces guys read this, please either update the online documentation or remove it. There are way too many components in there with information that has not been updated and is just plain wrong.