5 year old said i have her baby sister in my tummy

My daughter was laying down with me and had her head on my stomach and she just said out of no where that her baby sister is in my tummy and I said what did you say she said my sister is in your tummy. She’s been talking about having a sibling for a while and she would say things like that before but idk it felt weird that she said it this time. Has this happened to anyone and actually find out that they are pregnant after? I am suppose to get my period within the next week. I haven’t showed any signs of pregnancy. And with my pregnancy with my daughter I didn’t have early signs besides not getting my period.