I noticed in the first 12 chapters that teasing is something normal among the characters . It seems that everybody tease each other. The story starts with Mr. B teasing hiswife and thats continues over and over. Also Darcy teasing Lizzy and Caroline and vice versa. And here Charoline and her brother teasing Darcy:

"I would advise you, before you determine on it, to consult the wishes of the present party; I am much mistaken if there are not some among us to whom a ball would be rather a punishment than a pleasure."
"If you mean Darcy," cried her brother, "he may go to bed, if he chuses, before it begins -- but as for the ball, ..

And Mrs. B had the opportunity to tease him too :

"Yes, she called yesterday with her father. What an agreeable man Sir William is, Mr. Bingley -- is not he? so much the man of fashion! so genteel and so easy! -- He has always something to say to everybody. -- That is my idea of good breeding; and those persons who fancy themselves very important, and never open their mouths, quite mistake the matter."

Even the little boy Lucas teases Mr. B

"If I were as rich as Mr. Darcy," cried a young Lucas, who came with his sisters, "I should not care how proud I was. I would keep a pack of foxhounds, and drink a bottle of wine every day."
"Then you would drink a great deal more than you ought," said Mrs. Bennet; "and if I were to see you at it, I should take away your bottle directly."
The boy protested that she should not; she continued to declare that she would, and the argument ended only with the visit.