Dog Aggression or over-stimulation?

Lassard

I'm probably over-thinking a bit here.
I have never had a dog as a pet so I have no idea how to react to dog behavior. This afternoon while in my driveway a pet dog from a local house was on the road barking frantically & on seeing me, ran up my driveway and......"confronted" me, standing his ground & barking non stop.

I froze , not knowing how to handle this as it was acting highly agitated, in a restless crouch with teeth bared but with his tail wagging (as far as I know this signifies excitement & not necessarily happiness) . I genuinely felt that if I didn't do something soon I'd get bitten, as it seemed to be getting more and more wound-up.

As it was, I flinched at him & he shot out of the drive onto the road, still barking only to return a few minutes later to continue barking & growling at me from outside my gate.
While this was an unpleasant experience I would like to know if this is normal behavior for a domestic dog, even one who has maybe been inside all day. By the way, I've no idea what the breed is, it was a medium sized dog with a long snout.

DBB

Bearing in mind it can be difficult to know exactly what happened here without having seen it, it's pretty clear this dog was being aggressive towards you. Why did he pick you? I don't know!
But his low body posture, non-stop barking, and wagging tail (I'm guessing it was a rather stiff, tense wag, not a big wide, waggy wag?) suggest a level of fear, uncertainty and conflict, whilst the bared teeth are a warning that whilst he's feeling unsure, if he has to, he'll have a go. His conflict and underlying uncertainty about what to do next is somewhat confirmed by his running away when you upped the ante a bit.
It sounds like you dealt with it pretty well, but I would suggest the flinch that you did was a make-or-break moment that luckily went your way, and I wouldn't do this again!
When a dog is confronting you like this, the best line of defence is to keep still. If you must move, do so slowly and deliberately. Do not turn your back to the dog. Turn your upper body slightly to one side so that you're not square-on to the dog (which can be threatening), and do not stare at the dog, instead darting brief glances at him or watching him out of the corner of your eye. I'd be inclined to keep quiet too. Sudden movements, or attempts to verbally cajole a dog can be the spark that makes him increase his aggression further.
I'd be inclined, if possible, to go and have a polite word with his owner too. Without knowing the full story, it's not good when a dog randomly confronts someone like this, and the owner needs to know what happened so they can prevent it from happening again.