Dogs also need to re-adjust their time and schedule, similar to humans. You could re-train him to get used to your work and life by scheduling the time for feeding, walking, sleeping, playing, and staying at home. I would leave more toys (such as Kong) and treats and walk my dog longer than common before going to work if he has a little "emotion". Also, you could try other
tips to reduce separation anxiety such as gradually increasing your leaving time.