My dog ate exactly 3 ounces of milk chocolate roughly 4 and a half hours ago and has shown no signs of illness or any of the other symptoms I read about.
Should I be worried?

NO you should not be too worried but you should keep an eye on him /her. I had my 9 lb maltese eat a box of rasinets along with the box and she's fine..been fine. If you notice him/her acting different then take him/her to the vet. just keep an eye out..make sure there is alot of fresh water around.

Your dog will probably be fine unless it is a toy sized dog. Even then it may be fine since it was milk chocolate and you know the exact amount.
Here's a chart that explains the toxicity per body weight and type of chocolate:
netpet.batw.net/articles/choc.tox…
Dark chocolate is more dangerous than milk chocolate and Baker's chocolate is very toxic and lethal in small amounts.
A friend lost her Maltese last Christmas when it ate 8 pieces of dark chocolate.

It raises the heart rate for a time. I would call the dr. I doubt they will have you do much-baking chocolate is worse then milk for dogs. W/ a healthy dog, I don't think you have a problem.

My old dog Lady ate a whole bag of kisses and a box of russelstover's.

I don't know about your dog, but my entire family gave our dog chocolate for years and years and had no idea we weren't supposed to. She was a basset hound and had chocolate candy, choc. cake, choc. frosting, etc. frequently. She never had a problem that we knew of and it was years later before we even knew chocolate was bad for dogs.

Ive heard its baking chocolate you have to be worried about, but you can pour hydrogenporixcide down his throat to make him vomit, about a tablespoon. call you vet asap! dont wait!

my dog has ate choclat before. not that much though. i don't think it will do anything but you might want to wach your dog. i know i won't kill her but it is bad for her. since it was milk chocolat i think your dog wil be fine. it won't kill her.

peolple say chocolate is bad for dogs but its true but also what is tru is that different dogs react different to the chocolate some it does not affect them some can die while others get diherya and well it all depends in your dogs immune system.

How much chocolate it takes to be dangerous depends upon the chocolate – milk chocolate has the least amount of theobromine, the chemical that's the problem, and very dark unsweetened the most, and on the size of the dog. according to the source below, a 50 lb dog would have to eat about 9 ounces of milk chocolate to have a toxic dose, and even then some dogs would be OK. so if your dog was about 15 lbs, 3 ounces might be of some concern. but check out this link, and you should be able to get a good idea of what might be dangerous for your dog.