Our tax returns with the Turbotax software show GST credit $0. We are entitled to the credit. Should I be concerned since this will be auto calculated by the govt?

Credit is shown on one of your returns, check if you can see the credit on the second return. If you don't see it anywhere, don't worry, Turbo tax is  providing only an estimate and actual calculation are don't by CRA based on the income reported. If you are entitle to the credit CRA will issue it even if Turbo tax has not calculated the amount.