Just because you have 2 phones with this issue doesn't mean it's widespread. If it were, this forum would have the pitchforks out.
You just got unlucky. Get an exchange.
i had a faulty lock button...
i think it is pretty common. my gf lock button stopped working as well.
maybe not a widespread issue but it is common...
also remember macrumors probably only accounts for 10-15% of those using iPhones