Boyfriend has no time for me - should I worry?

I've been dating for a month an older guy (he is 34, I'm 20), and until now our relationship was going very well. We have an amazing passion for each other, we wanted to spend every minute with one another, we used to text every day, all the time. But for few days now he has been very busy, since he is working as a professor in a school, and plus he has some commisions to do, and he told me that he doesn't know when we'll be able to see each other again. We do see each other in school, since I go there frequently, and everything seems fine, but he has no time to text me, and plus, he told me that I shouldn't send him pics (we used to send nude pics everyday we don't see each other), because he has to concentrate on work now. I don't know if I should worry, and I feel bad every time I think like that, because I know for sure he has so much work, and he might earn a lot of money if he finishes this in two months, and he is already very tired. But still, I am worried because he has no time for me. I offered him every help, but he just wants to be on his own.