Do I need to amend my tax return if I received form 5498 after already filing?

Not normally.  Depends what it is for.  Did you make a contribution or do a rollover?  If you got any 1099R did you report them?

I made contributions. Did not receive 1099R. Thanks!

The form 5498 is informational only used to support the contribution/distribution amounts  you entered on the tax return ... if you correctly reported the contribution in the program there is nothing to amend.