IMO you and your partner should always communicate prior about whether it would be okay to wake each other up with sex, and not doing so is irresponsible.
I don't think being woken up with a sexual act you couldn't consent to is a good way to define rape. A good definition is whether the act was wanted or unwanted. There's a subtle difference here.
If being woken with a BJ was wanted, then it's not rape. But it could have been rape if it was unwanted. It's extremely irresponsible to pray and hope that the contact was wanted without establishing anything prior. Basically: it's possible to consent to something during/after the fact. But it's dangerous, and why risk being a rapist by doing it that way when you can simply have a conversation about whether it would be okay?