I would at least mention it to him, if he said "no", that would be that.
If he were asleep and I needed to say run to the store and get coffee because I just discovered we were out of it in the morning, I would try to wake him a bit.
Really though we discuss money and we really do not have a lot of it, so we budget together, so I'd probably know exactly how much he had, what it needed to be spent on etc
He probably wouldn't MIND if I didn't ask, but I would be a bit annoyed if he took any of mine without telling me, so I would.
I know lots of people that don't really care if their spouse takes small amounts of money, but I think you should always check first, not necessarily every time if your spouse has told you they don't care if you ever do, but at least establish it is okay to do so first.