The short answer is, yes, lemon squares should be refrigerated to keep them fresh for a longer period. But, why is that? Is it because of the lemon curd filling, which is made with eggs and citrus juice? Or is it because of the shortbread crust, which can become soggy if exposed to too much moisture?
Think of lemon squares like a delicate ecosystem, where all the ingredients need to be in balance to create that perfect harmony of flavors and textures. If you leave them out at room temperature for too long, the eggs in the lemon curd can start to scramble, and the shortbread crust can become soft and soggy. It's like a tiny science experiment gone wrong!