Well, join the club. I don't have rattles (not now, anyway), but I did for a while -- in the area of the CD/radio, just briefly, after I had some work done in there -- and
many TSX's have had rattles, coming from just about anywhere. The exact area that you mention isn't one of the most common sources, but it has happened. As to the cause, it seems safe to say that the fit of something in there isn't perfect. However, tracking it down isn't always that easy. It does seem that most people who have taken their cars in for rattles have had the problem solved, although sometimes it takes more than just a day and sometimes also it requires more than one try.
Polls on the TSX sites have seemed to show that
most TSX's have had some rattle problem. Whether that's totally accurate or whether more people with rattles just tend to vote, we don't know for sure. But it's clear that the problem is very widespread in TSX's. I have the impression, however, that the problem is getting less and less prevalent in the newer TSX's that are coming out. (When did you get yours?)
There have been numerous threads about this, here as well as on other sites. Here is a search that turns up a lot of those threads on this site. (A couple of these search results aren't about rattles but most of them are.)
http://www.tsxclub.com/forums/searc...id=17629&sortby=lastpost&sortorder=descending