It was a common factor with a lot of successful heroes back then, really - at Marvel in particular, of course, given that it was kind of Lee's trademark, but even at DC, where the characters were much more in the 'I am PERFECT' vein, people messed up every now and then. I can think of a number of moments in early Batman stories, for instance, where Batman and Robin have 'whoops! Butterfingers!' moments that would've gotten them killed, were they not very lucky people. I can remember one story in particular where Bats is so disgusted with a particularly egregious mistake he's made that he tells Robin to "kick me in the pants - hard - and don't ask questions!"