Why did Gladys blush so very much more than before, and say the 'sir' so stiffly?

'Then you may deny it, for it is not true. I have not changed, Gladys, since—do you remember the Alderney?'

Gladys' smile said that she did.

'But I am on parole, both to you and my father. I am quite ready to break it with your leave.'

'I must go, Mr Owen—Miss Gwynne will be waiting for me. Will you give my duty to the dear mistress?'

'I will take your love to her, Gladys, and keep half of it. May I walk with you?'

'If you please not, Mr Owen. I would rather not.'

'Are you happy? just tell me this.'

'Very—very. Miss Gwynne is so good. I can only be happy. Good-bye, Mr Owen.'

'Good-bye, dear Gladys,' said Owen, pressing her trembling hand that she held out to him, and opening the farm-yard gate for her to go out.