A score of 158 on the verbal section of the GRE is considered low, especially for competitive PhD programs like those at MIT and Caltech, where higher scores are typically expected. However, a perfect score of 170 in math may balance the verbal score, as admissions committees often consider overall application strength, including transcripts, research experience, publications, and awards. Engaging with admissions staff or potential advisors at these institutions can provide clarity on whether to retake the GRE. Previous applicants have successfully gained admission with similar verbal scores, indicating that while a retake may not be necessary, a strong overall application is crucial.