Hypothetically you were at someones house a few weeks ago preparing for a camp, they spend a couple of minutes talking to someone who is like family on the phone than before, hanging they ask if the person on the other end of the phone if they know when a certain event is than hang up.
Now you're about to leave and they ask you if you know when the event is, you say that you do but they don't directly ask you if you want to attend and have said nothing else to you about it.
Now the event is in a few days and you don't want to seem like a dumbass and ask/invite yourself along.