Not CT, but I might have an explanation.
Doing your back work before chest could actually enhance your performance.
Not strenght-wise, but technically.
When pressing, it is essential to retract your scapula. That way your chest will get more of a stretch- therefore rom and it will therefore better work your chest.
Doing your pulling exercises will help you increase the tension in your back and bring said improvements.
OR it might be because you’re actually bastardizing the program and trying to work back, chest shoulders on one day and ARMS on the next?? I hope you realize that you cannot perfectly isolate your arms on a back exercise and the same goes for your chest and triceps.
You’re basically carrying over fatigue from one day to the next, thus “feeling it better”