Why did Turbotax tell me to mail in my taxes this year instead of efile?

I finished my taxes and was told to mail them in this year. I'd never done it before but it's so much more hassle. Turns out I can't even check to see if they've started processing until weeks after mailing them, meaning I'll be running up on the April deadline if something doesnt work out. I have two questions then. It was never explained to me why Turbotax said I must mail them this year. I trust them but would like to know the reason. Second, do I ask for an extension jist in case there's something wrong with my filing? I mailed mine in the second week of March.