So for example, if you click to view the list of people who liked a post (here is an example), then you click an avatar in the list to view the Member Card, when you close the Member Card, you are not taken back to the list of users who had liked the post.
Another example: You click to view the results of a poll and it is opened in an overlay. (Sample poll to test it) Then you click the # of votes links to see who voted for each option and a second overlay opens. From the second overlay, you can open the users' Member Cards as well in overlays.
I think it would be a usability improvement to return to the first overlay when closing the second in these cases. Don't know how practical it would be though.