In The Outsiders, why is Ponyboy worried that he did not call out for Darry while he was sick?

Remember that by the time we get to Chapter 10 there is a pretty serious amount of tension between Ponyboy and Darry.  Darry is, of course, Pony's big brother and he has been raising Pony and their other brother Sodapop ever since their parents died.  Pony has felt that Darry is too harsh with him and they have been kind of mad at each other.

So Pony is worried now that he did not call out for Darry while he was delirious.  He is worried that Darry will think that Pony does not love him or care about him.