No problem. Ever heard of Ronald Reagan?
Her starting age just means that she more than likely will not serve on the court for 30 years. Which might not be a bad thing. But, if she remains healthy and retains an interest in the job, she might be around for 15-20 years. There are plenty of people who are vital and active through their seventies.
Stop insulting us old bastards! I've still got thirty years left to work.