I bought a Macbook Pro with Retina Display a little over a month ago. When I bought it, the trackpad could physically click fine, but I changed the settings to "tap to click". Today I tried actually clicking and the trackpad barely presses down and I can only hear a very faint "click" sound. I'm fairly sure that the trackpad could click fine yesterday.
I use my laptop almost every day for at least several hours. I do eat sometimes when I'm on my laptop but I don't think anything could get under the trackpad, could it? What do you think the problem could be? Thank you!
Yep, debris in the tiny gap between the trackpad and the aluminum can impede movement. Examine with a strong light and, maybe, a magnifier if hard of seeing to confirm.
Since the Retina is still under the base one-year warranty, best bet is to take it to the Apple Store. Believe me, they have a long history of seeing problems like yours.
Also, given your first brush with danger on the Retina, consider getting the two-year AppleCare extension later on. Only requisite is that you activate it before the base warranty runs out.