I've been having light brown discharge for 8 weeks after novasure. i passed a chunk of light brown tissue yesterday. is this normal? should i worry?

This is not uncommon: The tissue you described is the residual tissue burned during the ablation. I've heard it described by novasure patients like that. It's also not uncommon to have some bleeding after an endometrial ablation. Sometimes regular periods may return after several weeks to years. It is more common to have light bleeding. You should discuss this with your doctor at a future visit. It is not urgent.