Yes. You should have received a Form 1099-R. If you did a direct rollover where the old retirement plan transferred to funds directly to TSP (or gave you a check made payable to the TSP for your benefit) then Box 7 of your 1099-R should have Code G. If it was coded like this then when you enter it in TurboTax the program will automatically make it a non-taxable transfer. If the funds were paid directly to you and then you deposited the funds with TSP, then you will have to carefully answer some questions after entering your 1099-R.
After you enter(ed) the 1099-R, there is a page that asks "What Did You Do With The Money From [Retirement Plan]"? See Screen Shot below.
Be sure you indicate that you "rolled over all of this money to an IRA or other retirement account (or returned it to the same account)." See Screen Shot #2 below.
Answering these questions correctly will result in your distribution showing up as non-taxable.