Black Mark On My Betta's Head?

[KrystaK]

So my Betta Drifter has a black mark on his head. I just noticed it in the last couple weeks, so he may have had it for longer. 
I'm not really worried about it, as he is acting like his usual self, arrogant and picky
Anyways I was just looking through some old pictures fo my younger days and came across a betta I got my friend for her birthday. He was a beautiful fish, sort of silver with red/blue fins. In one of the pictures I noticed he had a spot on his side. I recall him having it and us being like 12, we thought it was just a birth mark. Well as I recall that mark (He had it for months... or possibly weeks, I can't remember) swelled up and eventally killed the fish - we assumed it was cancer or something. So I'm sort of worried this will happen with my boy now. I mean he's such a picky eater and all that honestly, if he went off his food for a few days I think he'd just up and de  
 
I wish I could get a picture but he's pretty camera shy  

 

[Wildbetta]

Personally I think that a black spot is nothing to worry about as that seems to be a common thing.  If the spot becomes raised, looks irritated, or gets "fluffy" or if he starts acting odd, then I would start to worry.  
 
Also I assure you that if he went off his food for a couple of days, he would not die.