Actually I'm guessing (wildly) from the way equipment is scaled, that monsters are not scaled according to the exact level you're at, but according to a range of levels.
For instance, the Nightingale Blade, which is one of the last quest weapons in the Thieves Guild quests, drains an extra 5 health and 5 stamina for every few levels you gain, up to a maximum of 25 at level 46. I got it at level 36 and it was 20 health and 20 stamina.
Having just leveled up to 36 and up till now chopping everything up (particularly in the last couple of levels) with disturbing ease, I was wandering around Winterhold when another dragon attacked (yawn).
Then it hit me with its dragon breath, and my life went down from 300 to about 30 in one go.
I had a look, and saw that it was an Elder Dragon, which I had never seen before. I figure having been at the top of the pile at level 35, at level 36 I've now reached a new range of monster difficulty. The problem is, from here on in, having already nearly maxed out my one handed and heavy armor, it's not actually going to get much easier fighting the way I'm used to against enemies of this difficulty (barring increasing my enchantment and improving my weapons etc.), which calls for diversifying my skill/perk set.
Makes things a bit more interesting, like.