Depends of what variety of bamboo. If is is Phyllostachys aurea or nigra, then I would cut them off. Some plants and especially grasses, can flower and then die; they are said to be monocarpic.

Most of the shrub to tree-sized species of bamboo are monocarpic, on a schedule of once every 20 to 100 years. On the other hand, most of the dwarf species bloom almost every year, and don't die afterward.
Check this out:
http://www.bamboogarden.com/when%20bamboo%20flowers.htm