I even tweeted a second time two days later.
Here's something interesting, I called customer service and they said I got bonus points for that tweet back on February 1st. I didn't send any tweets that day, but I bet yah there was a back door method posted here so I got bonus points for a tweet I didn't tweet LOL. May have been the same for others, it shows up as "2013 Diet Coke Heart Truth Twitter Bonus Points" in your redemption history.