Why did this split?

Hey all! So, I built a TV console out of white oak about a little over a year ago. I just noticed today that there is a big split in one of the ends of the top. I think I’ll have to do something about it before it gets worse, but my question is: did I do something fundamentally wrong in n the build, or is this just bad luck? There is another spot on the other end starting to split slightly as well. I’m assuming I did something wrong with the grain direction but wanted someone smarter than me to take a look. Thank you!