You raise a good question. I too took notice of his leaving to sign Porkulus. I am not sure about ‘ever’ but I have not noticed this being done a great deal by past presidents. I understand why it is being done and that is simply that Obama is still running for office. Believe it or not, he is campaigning for 2012. This is what it is all about for him. He is no leader, so this is what you are going to see from him; a perpetual campaign.
I think you are correct. He might also have some Bill Clinton in him and needs the reassurance that he is still idolized by the masses.