why does pip believe mr. jaggers may be jealous?

Pip thinks that Miss. Havisham had not told Jaggers of her intent to set Pip and Estella up. This, Pip surmised, made Jaggers jealous,

"From this last speech I derived the notion that Miss Havisham, for some reason or no reason, had not taken him into her confidence as to her designing me for Estella; that he resented this, and felt a jealousy about it; or that he really did object to that scheme, and would have nothing to do with it."