Jim,
I don't want to sound like a wet blanket so please don't take offense. You might be very qualified for what they are looking for today. But as more time goes by, you may fall in the qualification game. The interviewees are chosen by a computer. As you continue in your desk job this year, you may fall out of whatever criteria the computer looks at for recent experience. My take is the email was not an invite to interview...it was more of a "let us know when the time gets closer and we will take a look to see if you have all the squares filled".
They have so many applications to sift through...for class dates they need to fill NOW or YESTERDAY. There will be plenty of empty seats for you when your time comes. I'm sure your numbers and quals will still be highly desired when the times rolls around.