You say near freezing, so we assume it did not reach freezing. Though the newly place concrete will not gain strength quickly it should not be damaged. As temperatures rise during the day the warmer temperatures should allow more strength gain. Concrete has a chemical reaction to build strength, that generates internal heat. If freezing weather was expected, we would recommend use of a protective blanket on the concrete surface to help hold the heat in and promote quicker strength gain. Generally, in concrete we like to see the concrete surface temperature at 50 °F (10 °C) or higher in cold weather to encourage strength gain.