There is an inconsistency with how posts that get placed on the moderation queue update the last poster information. Here's the scenario:
1. User is on the moderation queue and replies to a topic, which gets placed in the MQ.
2. Moderator approves post and last poster information for forum and topic gets updated.
3. User goes back and edits post, which gets placed in the MQ again, but last poster information for forum and topic is not updated and user remains as the last poster until post gets re-approved for changes.

I'm attaching a few screenshots to illustrate as well. It also looks like the "posts pending approval" marker might not be getting added to the topic though the post has already been approved so I can't verify that.