I get the same warnings when it's super cold outside and sensors are blocked or after a good rain. I wouldn't worry about it as it clears itself.
I still wouldn't worry about it. Next time your due for service bring it up then. Mine will go off even when there is slight dust sometimes or even after I wash my car. It's random. I usually just walk around the vehicle with a rag and wipe the sensors. They are very touchy. I do believe there is a sensitivity adjustment in the settings somewhere that you can adjust.No snow or ice covering the sensors, and it hasn't been raining. It's an intermittent issue when the temp is within 10 degrees of freezing.