You should take into account that the DMT-levels in MHRB differs wildly between suppliers, and even between batches. Too make stuff even more complicated DMT oxidates to DMT N-Oxide over time (this can be converted to DMT before pulling though), so for best results your root bark should be pretty fresh. Other than that, it's up to you and your extraction. One big factor is how many pulls you did, over how long time you did the extractions and the amount used. Pretty much everything counts in, so I would say that it was partly luck and partly a good extraction! Congratulations!
When it comes to suppliers and their different root bark, I've heard about some selling (old) stuff that generates only about 0.5% yield. At the some time, I've heard about certain stores selling fresh powder from which extractions can pull over 2%...
There's a clear difference between what I say I do and what I actually do perform.