Well, prolactine induced gyno is extremely rare, due to use of steroids. GHB is not a steroid, right?
That's why, I brought the analogy with Finasteride.
To make it even more clear, when you said, that prolactin induced gyno is more common then reported...well, sorry, but it doesn't make any sence. Our main source of information, is what's reported. Speculation is not fair, I can say anything also...
I have yet to see a study that shows increase of prolactin level due to trenbolone. On a contrary, there's a study, that shows no effect of trenbolone on prolactine level in male cows(lol, don't know the proper name, bulls, may be?)
Now, be logical, in healthy males, like us, it should take some tremendous amount or effect of something, like Trenbolone or any other steroid (Trenbolone is just a steroid mimiking Testosteron, basically) to increase prolactine level to such a degree when gyno might devellope.
Be serious...