Packages do go lost and they can take longer to deliver for no apparent reason, that's dealing with the post office.  The person might be a lazy swapper, but I wouldn't say they were unless I had proof that it really was their fault that the books coming to you went "lost".

They could have had the books and didn't mark them received, but they could also have just been really nice to you and marked the books received before they got them and able to check that everything was OK. It is usually not advisable to PM a receiver before the lost date unless you have DC tracking that shows the book was received for a few days. Otherwise you just aggravate the receiver since it is logical that they would mark it received as soon as they get it so if its not marked received, it hasn't been.

Measuring the time one package takes to get delivered against another is an exercise in frustration. You can mail 2 books on the same day and the one going the farthest can beat the other one delivered by 2 weeks, its just unpredicable.

If you have problems you can always pop into Live Help or use the Contact Us link in lower right to contact the Team. Nothing I see listed here is something anyone can really do anything about though. You have a lot of suspicions about the member, but nothing concrete to show they are violating any of the rules or Terms of Use of the site. The site will not mitigate individual swaps unless they become abusive; misunderstandings or disagreements - they expect us to work out ourselves.

How long passed after you sent your books? Close to the holiday season, I think media mail does tend to slow down. And sometimes media mail is just plain weird. Like Melanie said, you can't really base anything on how quickly other books arrive. Sometimes one book will get across the country in three days, and another will take three weeks to get to a neighboring state.

Is this a new member? I think PBS does watch for unusual patterns of books going lost in either direction. So if it is deliberate, they should catch on to him/her pretty quickly.