Can you post a little more clear it is possible the employees was seeing something that indicated it was a Creamsickle. It is also possible that the breeder that the store works with produces them, and the employee knows this.
Like mentioned, depending on the % involved, they can still look very much like pure Cornsnakes, even though they are a hybrid.
If it was labeled as a Creamsickle, I would stick with that.
When it comes to hybrids, you do not want to claim purity, if there's a chance that is not.