I do know that if you place your fabric in the freezer overnight the marks will come back, my little god-daughter had great fun writing secret notes this way :)
But, I figured my work would never be in a freezer overnight, so all was well.
I have experienced the 'ghost marks' left on fabric, but, until the other day, I had only found this problem with the neon Frixion pens. 'Until the other day' being the important part of that sentence, as it seems the black one does it too. I have not found this issue with the dark green, the dark blue, the purple nor the red so far.
You can see the ghost quite clearly in this picture:
Here is an interesting article regarding using these pens for crafting and why we maybe shouldn't....