I "think" I remember when the die-off happened and you posted about it. I had thought before that bamboo had a reputation of taking over everything and being hard to stop once it got in the ground somewhere and I think you told me your weather might be the cause. Sounds like its roots didn't die with the tops. I'm glad it showed back up since you were originally sorry to see it leave.
It's kind of funny that you say you were so excited about it. :)
I was bereft when it karked it. Everything I read online said that that was the end and very rarely it could survive. I think some of it is the remains and some must have been one of the million seeds it dropped! Whatever though, I am over the moon!! :OD