The age 59-1/2 only affects you when you take a Distribution from your 401K.
If you put QDRO funds into your 401K, you may have a Non-Deductible Contribution to report.
Click this link for more info on QDRO Retirement Contributions.
However, you should have received a 1099-R from Fidelity to report the transaction.
You may be able to get this at their website if you didn't receive it by mail.
This link gives instructions on How to Enter 1099-R.