I read your question and I understand your concern. The reason they have told you that is because low platelet count is a factor for bleeding. There are many possible locations for bleeding, the brain being one of them which could cause headache. However the intensity of the pain when you have a brain hemorrhage is usually higher than what you describe and also usually associated with other symptoms like vomiting, weakness of the limbs on one side, confusion, visual symptoms (I don t mean all at the same time, depends on the area involved and its size). So if it is a very minor headache as you say I wouldn t go to the hospital right-away. If persistent or other symptoms appear then yes, you should be evaluated by a doctor. I hope to have been of help.