For the price of the Trend WRT router table, it is likely as properly engineered as one could expect. However, after looking at the parts diagram from the Trend site, it appears to be an easy fix to shim the back of the MDF fence to bring it perpendicular to the table top...assuming it was assembled correctly. It is also possible that the fence is faulty, so it's good that Trend will send you another fence,.
Tris was describing how to check the alignment of the two MDF fence sections along their length. If the two sections are not coplanar and aligned with each other, you could have a situation where the board you are cutting snags on the leading edge of the outfeed fence after it passes the cutter. The easiest way to check this, as Tris stated, is to lay a straightedge along the length of the fence so the infeed and outfeed sections are touching the straightedge. If there is no gap and the straightedge is in full contact (or reasonable contact) with the fence sections, then the snagging problem might be related to the the infeed fence not being perpendicular to the table and outfeed fence being perpendicular.
I have spent a lot of money traveling down the router table path of discovery before I ended up with a solution that works for me. Most of my expensive journey was before I joined informative woodworking sites, such as UKW. If I only knew then what I know now...
Fortunately, my wife no longer rolls her eyes when she sees me modifying something I spent hours and lots of money building earlier.