Gina,
may be its a cultural difference then, because I can tell you two instances where I went out with someone on what I thought was a casual offer for supper. In one instance, the girl later asked if she could stay at my place for the night, and it led to an awkward situation. In the second case, I got a text from the girl, a few hours after, saying she had a really good time and we should do this more often. Good enough so far, but she called the very next day to ask if I wanted to come to her place for a movie dinner.
So, I’ve actually experienced this situation, and if the other person says something like “it will be like a date” as in CP’s case, I’d advise him to make sure it isn’t being construed differently in each of their minds.