If they said that to you, I do believe you have an age discrimination case! Would certainly be worth talking to Legal Aid, or whatever federal agency is appropriate.
I retired @ 56, took some time off, then when back to work @ a lower acuity unit. I'm having a ball, getting paid well, and enjoying myself a whole lot. Fortunately, (and this is not true in most nursing jobs
) I get a good pension from my first job.
I will be 60 this year, and would like to work several more years. I'll just take it as it comes, I guess.
I wish you the best in your endeavors!!