This situation happens often enough, and it may be the result of some inconsistent data entry or the luck of the draw.
The IRS sets aside a certain number of returns if the data entries don't match the information that the IRS has received from other sources (for example, if you forgot to enter a 1099 form because you hadn't received it yet - the IRS already has a copy). Or the IRS may have flagged your return for extra review because of something that has a high likelihood of abuse (like EIC or Schedule C). Or the IRS might have just picked your return at random for extra review - if nothing else, a number of returns held for extra review that turn out to be fine tells them a lot about the quality of their review process.
This situation generally has nothing to do with how TurboTax did your return, nor can TurboTax do anything to reduce your risk of being reviewed.
You will either get a letter asking for more documentation on some issue, or you may get a letter reducing your refund for cause, and you may just get your refund in lieu of a letter. All you can do now is wait.
