A week or two ago there was some discussion of how well John Thorpe actually knew General Tilney. Thorpe has previously made claims about his acquaintance with General Tilney (Ch. 12):

"Know him! There are few people much about town that I do not know. I have met him forever at the Bedford; and I knew his face again today the moment he came into the billiard–room. One of the best players we have, by the by; and we had a little touch together, though I was almost afraid of him at first"

Compare that, though, with the account now revealed in Ch. 30:

"The general, perceiving his son one night at the theatre to be paying considerable attention to Miss Morland, had accidentally inquired of Thorpe if he knew more of her than her name. Thorpe, most happy to be on speaking terms with a man of General Tilney’s importance, had been joyfully and proudly communicative."

I'm led by this to believe that Thorpe had never met the General before this moment! General Tilney saw that Henry was paying attention to a pretty girl, and asked Thorpe for information because he saw that Thorpe was part of Catherine's party. But when Thorpe is telling Catherine about the conversation later, he cannot help but maximize his importance by making up some story about his prior acquaintance with the General, as he inflates everything that might reflect well on himself.