If you're doing it to spread useful information or to get help then it's OK, though it is common courtesy to say on each forum that you are posting to multiple forums in the hopes of giving or receiving the max possible help.
If you are doing it to start something and don't say you are doing it then you are a troll and deserve everything you get.
Obviously, the second case doesn't apply to you. I'm just sayin' it's important to be open and honest. If you don't explain, you leave yourself open to accusation, which would be a shame.