Did you have Self-only coverage instead of Family?
I take it from your question that you went back and changed your return in TurboTax to say Self-only, and your adjusted gross income (AGI) and tax due did not change.
In this case, I would not amend the return, but I would make some good notes about what happened in case you ever receive a letter from the IRS so you can explain what happened.
Note, I am assuming from the "Return did not change" that you went back into TurboTax and changed the plan from Family to Self. Did you go all the way through the HSA interview before looking at the AGI and tax due? There are questions all the way to the end (when you are returned to "Your Tax Breaks") that can affect the return.
My concern is that in switching from Family to Self, that you might have excess contributions because the annual contribution limit for Self is about half of Family. But if there were no excess contributions reported when you made the change, then do as I suggest - keep good records and don't amend.
NOTE: next year, when you are asked for what type of coverage you had in 2017 (yes, two years before, like TurboTax asked you about 2016 this year), be sure to accurately enter "Self".
