I've read an analogy that finding iron-rich galaxies just 900 years after the Big Bang is like finding an old man in a crib in a nursery. We just recently found a supermassive black hole 12 billion solar masses at Z > 6. Our current understanding is that a Black Hole this size would take billions of years to form, yet there it is just 900 million years old. There is also the Methuselah star in our own galaxy that is on the very edge of the margin of error. What other evidence is there that the universe might be older than the currently popular age of 13.8 billion years?