Am I overthinking all this?

My boyfriend and I of over two years were hanging out today and trying to decide on a place to eat. He recommended a pizza place and I said I’ve never had it before and he said yes I have. He said he took me there a while ago and remembers I ordered a plain cheese pizza and he got something that was all his favorites on it. We’ve never gotten pizza together. Ever. I know that because I’ve been wanting to get that with him for a while but we always choose something else. I told him this and he started saying “huh” and then said it must have been a dream and it must have been one realistic dream and he could’ve sworn we went. I then asked if maybe he’s mixing me up with someone he’s gone with before he met me and he said no he remembers it was me. I let it go but it still makes me wonder if it was a date with someone else. The problem with this is he said he’s never dated anyone before me.