I'm not sure if it is the same as my daughter had when she was a baby, but it looks exactly like what she had.
When she was 4 weeks old, I noticed a red bump/lump on her head, I immediatley took her to the doctor, and it was diagnosed as a "Hemangioma"
( If you google Hemangioma it might help you) They are not serious, and they do subside over years.. ( Now a days they can even be lasered off). But in the case of my daughter it eventually just faded, and even the bump/lump has disappeared..
My daughter is 27 yrs old now and every now and then I take a look at where it was, it is now just a little red mark..
P.S. There also was a little boy in my son's playschool who had one on his forheaed, and he had it lasered off, and you can't even tell where it had been.