Recently due to my problems with my DVD drive I decided to take the drive out of the computer and discovered that a B size chassis screw was missing from under the drive... there are 3 holes, and there are only two screws, the left-most screw was missing (see picture).
I didn't even know those screws existed, so it wasn't me that removed it. I bought the computer from a Tigerdirect.ca location as (what I thought was) new... is it possible they sold me a refurbished model? The guy handed me the box at the store...
Though, this might explain the circumstance where my computer randomly crashes: someone else bought it, discovered the problem, took it back, then they just sold me that one, perhaps without knowing the problem existed.
Am I being paranoid? Or is this a thing that happens?

TL;DR: Took out Disk Drive, found a screw was missing that I had never removed. Did they sell me a refurbished model without telling me?