Yeah you betcha - should DEFINITELY check that there's no faults before applying those stickers!!
By what you describe, it sounds like the stress mark is on white plastic??? (i.e. visible black marker line)... or is it on black plastic, in which case it should be difficult to spot the black marker right?
I had a problem with those black ramps that form the base of the forefeet... very easy to forget to fold them out when transforming from city mode and then if you try to make the legs for robot, you end up stressing the ramp, which leads to guaranteed white stress marks on black plastic... Grrr!