If the OP was an Android user before, the immediate expectation is that it wouldn't be made available so as to encourage users to junk their old but perfectly good hardware into landfill and buy another. Rude, I know, but that's the Google way it seems. No further reason required.
OP, don't be worried. It works differently here. Unless there is a real hardware reason to deny the upgrade, you'll get it. That is unless you are with AT&T in the US I hear, as according to this forum they hate all their customers. In the UK though (and almost everywhere else) you will get the update unless your hardware truly can't run it.