On my first day at work, after work, the manager said I looked tired, too, and told me to go back and have a good rest. I was a food cashier, and she really cared.
It may be just polite words, or it may be just words of concern among colleagues. You don't have to think too much.
Besides, since you are the manager, you must have met many people.
On your first day at work, he naturally won't judge you.
So, you don't have to worry, just go to class normally.