What's happening to my Yucca plant?

I have an indoor yucca plant that I've had for years (it's about 3 ft tall). Recently I noticed a long narrow stem, about the circumferance of a pencil growing out of the top of the main part of the plant. about every four inches there's a circle of green bulges on the stem. The stem is about 2 ft long and exudes sticky goo. It literally appeared overnight. What is it...a bloom or something ? I'm hoping it is some sort of flowering. It's never happened before.