There are short-term questions as Chipotle transitions to new leadership, but it should maintain its momentum.On June 18, fast-casual chain Chipotle Mexican Grill (CMG 0.07%) underwent a 50-for-1 stock split, one of the largest in U.S. stock market history. Stock splits are typically done to lower a company's share price and make it more accessible to more investors, so it was very timely for a stock that has been one of the best-performing in recent years.In the five years leading up to its stock split, Ch ...