there was a similar post about 4 months ago.. (i think that long lol)

my ds used to be a real bad nose bleeder also, weather, gravity, certain movement would set off a water fall..

Its not a severe thing to happen but there is measures that can be taken to stop this from occuring if it becomes regular..
go see the gp and just see what he thinks..
sometimes they will burn capallaries (sp?) which is a cause of most nose bleeds..