I don't honestly know if it is normal or not. I had never seen that happen before after mating.
Did you deliberately want your dog to be mated? Are you happy about that -and do you have good plans for all the pups? Remember, finding loving permanent homes for them isn't as easy as it sounds. Very many adopted pups end up in shelters because the people who adopted the pup don't want it when it has grown up....or they are moving house...hundreds of different reasons why people dump their dogs! (Yes awful, I know.)
If you didn't particularly want it, there is a "morning after pill" for dogs. But of course you would need to take her in to the vet very very soon, either today, tomorrow etc
Then you could also ask the vet about what you experienced.
Actually....why don't you do that anyway, even if you are happy for her to be pregnant? You could simply make a phone call to the vet's office to inquire. The receptionist of course may not know, but ask to speak to the head vet there.