Although I love Reed, I do feel as if one of their major downfalls is their computer system, especially in the application process.
I also interviewed a few months ago and got the same email recently. I am of the strong belief that they just send out mass emails to their mailing list, without much other discrimination. There have been other Reed related events I have attended and then got invited to a few months later. Their email software does not seem to be particularly complex.
I know this is quite a bit later, but I hope it is still helpful! I would definitely not sign up for another interview unless something in your life has drastically changed and you feel the need to sit down with an admissions officer to explain it.