I've had false pregnancy in bitches pretty regular. I've visited with several vets and there is nothing they suggest other than regulating feed, water and giving the bitch time to get over it.
I feel like environmental pollutants and poor feed may contribute to the issue as much as genetics. Best to keep your bitches healthy and clean and as free from pesticides as possible.
You could run your bitch on TMZ after her next heat cycle. It won't hurt to try it. Or just let her naturally go through the motions to see whether or not this was a fluke occurrence.
Good luck,
S_B