Being admitted for a shorter period does not automatically mean you violated the law. Customs officers have discretion to limit the length of stay if they have concerns.

As long as you leave the US on or before the date on your I-94, you should not have a problem. Overstaying that shortened period would be the real issue.

This can sometimes show up in future visa applications, but it’s not fatal. Just be honest and show that you complied with the terms of your admission.