Let's be honest, if the glass screen cover is not sealed to the machine - which I don't believe it is - this will produce condensation behind the glass if the conditions are right (or wrong), and this constitutes a DESIGN FLAW. It should not happen. Of course if you mollycoddle the machine, check the temperature and humidity every time you turn it on and so on, you will be able to minimise the occurrence, but that it happens at all is a DESIGN FLAW. Somebody did not think it through at the design stage. It may not be particularly serious, but I certainly would be pissed off if it happened to me. I want to be able to just switch the bloody thing on and get computing. If it happened to a laptop nobody would argue that it served the OP right for using it outside, would they?I agree that it could be a manufacturing issue due to where it was manufactured, but the fact that the glass cover isn't sealed on the inside strongly suggests to me that it's due to air which circulates inside, not due to air from where it was made - and it'd surprise me if these were made in highly humid environments.
Still, yes, it might be a defect - and I've seen plenty of other Apple design defects over the years - but this strikes me as more likely being user error.
As for "user error", you surely cannot be serious.