Wait, how can a number of steps be wrong? It's just a count, so whatever you got is the right number now. Honestly that's just messing with your own memory.
What if the house settled over time? My grandma's place had a step that basically disappeared into the floor after 40 years of the foundation sinking. The top step became way shorter, so the whole rhythm of the stairs changed. You might be remembering the feel from when you were a kid, but the actual physical count could be different now.