I think that Ben's closeness with the Island isn't what it once used to be. Richard told John Locke that he and the Others were sick of Ben focusing soley on the child conception issues instead of what was really important. Ben has been using the Island for his own selfish purpose. While solving the pregnancy problem on the Island is important, it's not the true main purpose the of the Others. I agree with you all that Ben's tumor was the Island's reminder to Ben that he is swaying from the true purpose the Island has intended for him. Just my opinion, though.
