She has daily hiccups that last for a few minutes and then are gone. Various times of day, sometimes in the middle of the night. Doesn't seem to relate to eating food or drinking water.
This happened a lot to my puppy when we first got him. The hiccups decreased around 4 months for me. I agree with the person above who says that if they don't go away on their own or if she is experiencing distress, it's time to see a vet. Hiccups are very normal for puppies.
This isn't an issue I've encountered with my dogs, or any of the dogs I've watched, but a little googling leads me to believe that, like in humans, hiccups in dogs are rarely cause for concern. It's just involuntary contractions of the diaphragm and usually quits on its own within a couple minutes. These articles go a little deeper into some of the common causes and cures:
http://animals.howstuffworks.com/pets...
http://www.vetinfo.com/dog-hiccups.ht...
http://www.dogingtonpost.com/how-to-c...
I know from personal experience that getting the hiccups tends to go in phases. It's a lot like biting your cheek. Once it happens once, I'm more prone to it happening again and again, and that cycle can last for a day or two. Then I'll go weeks or months without getting them. Since the mechanism is the same in your puppy, she may go through periods where she gets them easily and frequently, and then they'll stop for a while until something triggers them again.
If they don't seem to go away on their own, or with the help of some of the tips in the article, or if she seems to be experiencing distress, it may be time for a visit to the vet to make sure there isn't something else going on.