Harassment based on age is against the law. This rule generally protects individuals age 40 and over (and in some states under 40).
If her coworkers continue to subject Gladys to age-related comments and jokes, or attempt to exclude her from office activities because of her age, their actions could interfere with her ability to do her job. And if their behavior is severe or persistent enough, and if a reasonable person would also find it offensive, it could even be seen as creating a hostile work environment and lead to a claim of age-related harassment.