To be honest with you, I highly doubt it was caused by the use of T3...
Perhaps a combination of many things, but doubt very much it was because by T3 consumption.
Also, I believe Tren lowers TBG (thyroid binding globulin) significantly. I'm not positive that this is the leading reason, but it is very common with other AAS, Cortisol, HGH, etc....
Give this a read:
http://www.mindandmuscle.net/content/page-197.html
EDIT: Wait, you mean after Tren is discontinued? Perhaps it's because the TBG is still suppressed temporarily? I've never ran Tren, but that would make sense... temporarily I suppose.