This is the top of my head: Undreaded section of hair (it is composed of loose hairs that don't rightly belong to any dread) OR Precursor to a bald patch? I know dreads will tend to migrate from the top of your head, but there is enough visible scalp to have me worried. Going bald from the centre out is not a good look on anyone.
It could also just be a cow lick or a double crown. I have a section that sorta looks like that and it's just how my cow lick sectioned out.
That was how my hair started to look in the back which is partly why I combed out, I was worried the dreads were too heavy for my very thin hair. Looks fine now so I wouldn't be too worried about yours.
The density of hair in that spot looks a bit low. Get some high resolution pics so you can see roughly how many hairs are growing there, and then get more after a while, to compare? If it is a baby bald spot....... don't cut
i have a baldy patch too, tho i think its from a bad time in my life, and i pulled my hair out due to stress..
If you look at my 2nd pic here : http://www.hipforums.com/newforums/showthread.php?t=408085 you can see somethign similar to your. I was worried that i was going bald too! Hmm perhaps I still could be, havent checked in about 6 months