Yeah, I suffered a sneak attack by two wolves (two separate incidents) on day 1 and two in my new game. But that's pretty realistic, isn't it? I mean, otherwise wolves would catch didly-squat, if the prey always knew they were around. They are scavengers, yes, but they hunt in packs, too - very sneakily!
However, I was pleased to find I was able to kill the first one with my grade 1 metal-reinforced club with zero damage to my character, and the second one went the same way, though I lost 25% health.
In real life (yeah, it's a game, but come on....) if a pack of wolves set about you on your ownsome, you'd be dead meat.
People used to complain about the dogs doing this, and I - who never plays on hard settings - always thought "wimps!".