It is uncommon but not impossible that opposite site symptoms occur. Positioning during surgery could have put pressure on opposite side ankle nerves which could leave a numb heel temporarily. It is possible that a small fragment of disc migrated to the opposite side or even a seroma (collection of fluid) is causing some compression. You could ask for some oral steroid which can take down symptoms faster that just “Father Time”. If symptoms don’t resolve in 5-7 days, you could also ask for a new MRI.