Fullmetal Alchemist question?

I was watching FMA the other day and this is just speculation and I am not sure if it actually has any significance in the series but it seems that people that have seen that truth also have the flamel cross somewhere around them. Dante, Ed, Al, Izumi and I haven't seen it on others yet but those I have seen it for sure. Its seems to be the opposite of the homunculus tattoo. Like a tattoo for the alchemists I guess. Has anybody else noticed this and if so what are your thoughts on it?