Thanks for answering my questions. When we suture the skin after a surgery, we generally will put in buried sutures that will hold things together even if the skin ones get removed, so there is a good chance that things will be just fine. But since I was not present at your dog's particular surgery, I cannot say with 100% certainty that this was done, so be sure to watch things closely.
First, if you are uncomfortable with the situation at all, don't be afraid to have her checked out by a vet. I know it is a weekend, but every clinic should have arrangements made for after hours emergencies that come up - if you call your regular clinic you will likely get either an answering service or an answering machine that will tell you how they like to have these things handled. If you want her checked out to make sure everything is okay, just let them know that. You may end up getting referred to an emergency clinic, which will probably be a bit costly, but if it gives you peace of mind it will be worth it. If necessary they can replace the sutures.
As long as there is minimal gapping or swelling and no bleeding, then you may be able to deal with this at home. Mostly we want to give this area a little extra protection and prevent her from licking at it - What generally works pretty well is to use something like an ace bandage to wrap all the way around her belly. This will protect the area as well as giving it a little extra support. Use some type of non-stick bandage right up against the incision (like a Telfa pad - you can get these at any department or drug stores) If you use this type of bandage, I would still take it off twice a day and take a good look at the incision to make sure things are healing well, and then put it back on again.
You can get an E. collar (one of those cones that fit around their head to keep them from licking) from a local clinic or pet store but I would still use the bandage since it has been less than one week since her surgery just to be on the safe side.
If you see that the gaping is enlarging, if there is increased redness or discharge of any type, if there is increasing swelling around the incision, if your dog is acting lethargic or painful or stops eating, have her checked by a vet immediately.