It's a pretty easy typo to make. I was an English major in college and am still fairly conscientious about these things, but our entire culture of quick text-m

It's a pretty easy typo to make. I was an English major in college and am still fairly conscientious about these things, but our entire culture of quick text-messages, status updates, and all the of-the-moment acronyms that those entail is fairly antithetical to any kind of grammarian proof reading. Educated people often intentionally dispense with the apostrophe simply to save time, safely assuming the other person knows their meaning.