They say anything at that age !? Could just be an invention ( back door excuse) because she was happily playing and didn’t want to go out. Our DGD (same age) said that she didn’t want to home yet ( she was enjoying herself here ) because a burglar had taken all her toys.
You could try putting some stickers on it? At that age my GS wouldn't go down my garden because I had some dragon statues he found scary. So I dressed them up in cheap necklaces, sunglasses and hats and he stopped worrying about them.
Mum to 4 year old: "would you like to go to granny's?" 4 year old: "No." Mum: "Why not, I thought you liked going to granny's." 4 year old: ".I'm scared." Mum (a bit shocked by now). "What are you scared of?" 4 year old, very definitely: "The back door.' Mum, very puzzled."Why?" 4 year old. "It's too white."