I've never seen a blooming dracena before, but my co-workers plant started to put out a spike two weeks ago, and it's now about 18" long! It's right in a window well, and gets afternoon sun for several hours a day.
The bonus has been the fragrance -- it's incredible! A cross between lilacs and jasmine, and so strong it perfumes the entire station by the end of the day.
For all I know this is a common phenomenon, and I've just seen light starved dracena, but this has been a revelation to me, and I wanted to share.