Doesn't sound like you had to surrender the medical.
The medical certificate is never valid if you're not medically fit to fly: it's only valid for that time when you meet the medical standards, so having a condition which does not meet the standard and holding the medical certificate in your possession are not incompatible. If the FAA didn't revoke your medical, then you may have been ill advised to surrender it or return it (unless it was in the hope you'd come off the medication in the future, and returning the certificate would preclude dealing with the issue of revocation or suspension).