I have a friend who is kind of like that--I think we've made plans only to find out that they were more ambiguous to him than they were to me (though if we've solidified plans he would probably not back out of them). How solid were the plans between the two of you? Because I find that, between my friend and I, sometimes I think that our plans are really solid when to him they were a mere suggestion. If he's not in the habit of blowing you off, I'd say maybe chalk it up to a miscommunication. Talk to him about it later and tell him how you felt so that it doesn't happen again.