yea the driftwood I have is over 2 years as well and its also still releases tannins. Must depend on the type of wood, I got so sick of the dark water in a few of my tanks that I was forced to remove it.
It seriously depends on the wood. Of the unknown pieces that I have collected and used, I have had some that bleed a little, some -none and some I just threw away because I could not stop them from tinting the water.