Pip asks for a sum close to 900 pounds for Herbert. Being a relative of Miss Havisham's, Pip sees little reason for Havisham to say no and he feels a certain level of guilt for what he's put Herbert through, so he risks a chance encounter with Miss Havisham.
This shows that he is willing to sacrifice for someone he cares about and that he sees a need for equality or a sense of duty in the world. I think he thought he "owed" this to Herbert.
I think that the part you are asking about comes in Chapter 44. It is right at the beginning of that chapter.
In that chapter, Pip asks Miss Havisham for money, but it is not for him. Instead, he is asking her to arrange for Herbert Pocket to have some money without him knowing how it came about. He wants Herbert to be able to succeed in business and he thinks that Herbert has been much nicer to Miss Havisham than the other relatives (so he doesn't deserve to be punished).
To me, this shows that Pip is a generous and unselfish person.