To Wake Up or Not To Wake Up

     I've read in multiple places that you should never start your book with your character waking up. It's like a death sentence for your book.
     I get that, I really do. But...
     I have always assumed that what this means is something like this:
     My alarm blared, waking me from a lovely dream. I groaned. I hated getting up in the morning. After laying there for a few minutes, willing myself to get up, I finally ambled out of bed. My greasy hair clung to my head so I sighed and stepped into the shower. The hot water was enough to wake me up. I quickly dried my hair and dabbed on some makeup and then went down to breakfast.
     This is of course an example of weak writing all around, but you see what I'm saying here? I thought that the whole not starting your book with your character waking up meant you shouldn't give a blow by blow of their everyday routine before getting to the action that happens later in the day.
     Why am I even mentioning this? Well, the first line of my book, Daze and Knights, is this:
     I woke up to a sword at my throat.
     You see my dilemma? My character starts the book waking up. But, I'm starting the book right where the action starts. I mean, hello- she's waking up with medieval knights poking a sword in her throat and she's wondering where she is, who they are, and what happened to her bedroom. I thought this was fine. I never considered it fell into the category of "waking up". Then someone who critiqued it suggest I change that. And I thought- Ack.
     And THEN- I read a post by Nathan Bransford (you can read the whole thing here) who says you should NEVER do it, no matter what.
     I do have a reason for her waking up- an important reason that won't be explained until a later book (if I get that far). I'm not just doing it because I feel like it. But I don't want to hang a death sentence over my book or make it easy for agents to scrap it after the first line.
     So- what do you think? Should I change it? Comments? Bueller?