Is some warning too much to ask? Or do I have unfair expectations? Isn't the freedom to just hang out with your friends at the last minute without having to run those plans by anyone else the situation of a single person?
Personally, the way I have always looked at it, this should be a luxury of any relationship unless you are married. Once a couple gets too wrapped up in the "usual", it will occasionally become "normal" and boring in the long wrong. Or lead to a definite path of marriage due to expactation.
However, there are 2 sides to this. If you guys ALWAYS do dinner together, then of course you have a reason to be upset. He should have called a little bit in advance.
But, if its dinner "most" nights, or every now and then, its not really anything to get too upset about.
A lot of times people get so wrapped up in the "norm" of what a relationship is "supposed" to be, or what is expected...when the reality of it is that when you are simply dating, you should be pretty much free to do whatever you want with your own personal time. (Within reasonable limits of course, cheating and whatnot excluded.)
So he changed things up one night. Dont forget, he is still a guy, and guys will always do guy things. The more you try to control that, or keep him from feeling like he still has some freedom in the relationship, the more dissent can brew in the long run or him getting ideas that you are "too controlling".
Let him know what you were thinking, and politely remind him that you had planned on him coming over this night. Perhaps from this episode he will realize that next time he should give you a little more warning. But, dont press the issue and demand that he "check in" with you all the time.
Boys will be boys.