I'd recommend you e-file an extension (you can request an extension as many times as you like).
See Can IRS extensions be e-filed? for help in filing an extension.
There are two ways to file an extension using TurboTax online programs: an e-file extension and a printed extension that you have to mail.
If you did not print and mail a Form 4868, then you may not have finished the extension process.
If you e-filed the request, you should have gotten a confirmation from Turbotax.
