normally changes in systems can often spark flowering. There are schools of thought about plants like Vals flowering, some say that when they do flower is can be bad, as when they flower in the wild, they drop there seeds and then die off til the next season. Others like Aponogetons/anubias throw flowers off for laughs and don't die off.
Vals doesn't often flower in a home aquarium. One thing i have observed is that a massive temp drop can induce flowering, but you have to be careful of the livestock. Again, as in the wild this can imitate the change of the seasons.
