Wisdom teeth removal/ sinus issue?

Hello, I’m a 25 yo with 4 impacted wisdom teeth to be removed next month. Upon setting up the appointment the office staff showed me my panoramic x-ray and said my sinuses are close to my upper wisdom teeth roots and they informed me that if my root is too close in proximity/touching the sinus that an additional charge incurs and it wasn’t well explained but it sounded like there are additional considerations or modifications to the procedure which incurs that charge. It is about 1K per affected root/sinus. They also said it’s very low probability it will occur. Can anyone confirm if this is normal? A family friend with experience in oral surgery who hasn’t practiced in a few years said it sounded shady. Is this shady? Is it normal?