Well, it might really be true and your drive may be dying… I have experienced something similar on good quality media, where I was sure of their quality. It started after almost 2 years, a countless number of DVDs had been burned with it.
I did not worry about it for long and replaced it with an Optiarc 7203A, a miraculous burner!
But I have never had good experience with TY03 (or whatever their code may be) from Verbatim, they have always turned out to be so bad that even their TRTs weren’t smooth!
But remember that the TRT is the ultimate test, so I would be worried about the heath state of the drive, regardless of the other things! If the media is O.K. (which I doubt), then the drive is bad. The TRT must be smooth, or else something is wrong!