I haven't, but a friend of mine's baby girl showed one of these at her 20 week scan and she is fine and healthy.

As others have said, they aren't uncommon and most often disappear before birth. The fact that no other abnormalities were seen on your scan is really reassuring that your baby is fine

All the best, try not to stress (I know I know) and hopefully it will be gone next time they have a look.