How do I keep my new digitizer from touching the LCD?

I followed your instructions for replacing the glass digitizer on my EVO 4G. Everything went great but a day later I noticed what looked like a bubble in the center of the screen. The bubble kept growing with use.

With a little investigation I realized it's being caused by the digitizer touching the LCD. If I pry up the edge of the glass a little it pulls away from the LCD and the "bubble" goes away.

While none of your current solutions come out and say it, it seams like it is important to have a good seal around the glass. Can you confirm this. I used dabs of cement at the top and bottom of the casing. Was that a mistake? Will one of those 3M EVO glass adhesive things fix this problem?

I'm about to change the glass on a friend's EVO and I'd like to avoid this problem on his.