Dear Lennie, should I be offended is a guy cancels plans last minute and doesn't apologize or give a reason?
Offended? No. Extremely cautious? Yes. I am assuming he either cancelled by text or by voicemail, because you would have had an opportunity to ask him why if you actually spoke to him on the phone. While you could ask 'why' in a text, you're more likely to just say 'no prob' or something benign and non-confrontational like that. If he did not offer up a reason and apologize, I would not contact him whatsoever. Wait for him to contact you. If he does not contact you within 48 hours, assume he never will and that he was wimping out. Clearly he doesn't value you. If he contacts you later than that, it had better be a death in the family (heaven forbid) that stopped him from contacting you sooner. There is no reason for that kind of flaky behavior. And, if he's going to be that flaky and disrespectful before you even start dating, why would you want to date him?