Wow, a bit surprised to hear that! What kind of tricks are we talking about? I've been on their $5 plan for over a year and have never heard anything from them about upgrading!
Interesting, they used to offer a 10GB plan for $5 (which I've always been on: http://d.pr/i/WDEK ) . Apparently it's not available anymore! However, I was never asked to upgrade my plan (I didn't even know the plan I was on didn't exist anymore before today!)