You're just lucky the WGA verification process is so simple and doesn't really check much ....
One might say Microsoft are more interested in perusing this sort of mis-licensing stuff higher up the food chain than the end-user (i.e. at the reseller/distributor level), no doubt Microsoft are happy that you are using a legal-ish copy rather than some dodgy copy you downloaded or picked up when you last flew a far east routing. But I'm in no position to comment, and, as with most things Microsoft, I wouldn't be surprised if their stance changes tomorrow. But in your case I think the reseller is probably partly to blame as it sounds like you genuinely did make some effort to enquire before hand and the sales monkey just didn't know his X from his elbow.
If any mods are reading this thread, perhaps we can have a Microsoft Licensing Basics sticky thread ?