I have never even heard of a dog hiccuping in their sleep before, but it doesn't seem to be bothering Sadie, if she is able to just sleep through it. Does she eat right before bed, or maybe drinks, and gets air along with it ? That seems to be how I get hiccups on the occasions when that happens to me. Does it last very long, or does she just have a couple of them ? Maybe she dreams something that causes it. It is a really strange thing, whatever is causing her to do this.
What I can find online seems to say that this is fairly common, and is not anything to be really concerned with unless it lasts a long time, or appears to be causing the dog to have distress.
http://dogcare.dailypuppy.com/would-adul...-6215.html
| 
