joerocker,
If you did your due diligence and thoroughly checked out your builder in advance, then you should be just fine. He was probably not only moving the dirt closer(to save dozer time) but also mixing the dirt to get the best composition.
If Bahia does well in your area, then I'd go with it myself. If you have trees around or shade the Bahia won't do well..it needs full sun and hot sun. The roots on those plants are something else. To get it started, just buy you some bales of Bahia hay and spread it where you want it to grow. I've done this successfully on several ponds...the hay cuts down the erosion and next spring you will have seed germinating without ever having to buy and spread seed.
The only problem I have with Bahia is if you get good rain and hot conditions, that stuff will grow like crazy and require mowing pretty often. Common bermuda may not require as much mowing, but it also doesn't have to root system of Bahia.
