Boyfriend looking at other girls on Facebook, wrong/right?

Let me start by saying that I have an excellent relationship and I do not doubt for one minute the my man does not love me...However when he told me he was laughing at some random girls photos on Facebook it made me feel uncomfortable as she was not even his friend, he had to search for her via another see he tells me that he always looks a photos on FB when he is bored in work, which is fine as I know he is a nosy thing! Anyway cos I felt a bit insecure I decided to check his internet history (bad I know) and there were loads of girls profiles (including a number of his ex's) he had looked at and all their photos etc. I felt a bit weird but I keep saying to myself that its innocent and that he is just nosy. Am I to be concerned about this? and even worse I went to check his internet history the other day and he had cleared it, which makes me even more suspicious...I know he is entitled to privacy but I don' feel the need to look at men's profiles and photos so why does he look at other girls?