Here is a copy of my post on another forum:
"I noticed 5 bubbles inside the glass at the top of the driver's side of the windshield. They only became apparent after the summer heat kicked in. I took it to a glass shop who advised me that the bubbles are inside the glass, within the laminate film whih is sandwiched inside 2 layers of glass. This is a defect from the manufacturer (PPG) and it should be covered under the 3 year bumper-to-bumper Toyota warranty .... my advice - wait a while before you get them to replace it ... wait until you get a nasty stone chip / crack ... then you can get a new windshield for free, without having to make an insurance claim."
http://www.matrixowners.com/modules....opic&t=120