Scherzer (back/thumb) threw a bullpen session Sunday, Keegan Matheson of MLB.com reports.
The 41-year-old had his rehab assignment paused last week in order to get three cortisone injections in his right thumb, but he wasn't shut down from throwing for long. Scherzer originally landed on the IL in mid-June due to back spasms, but he's now received cortisone injections for both his side and thumb while on the shelf. The Blue Jays hoped that the right-hander's quick return to throwing will allow him to resume the rehab assignment in the near future.