High blood pressure, but not really...

I am almost 35 weeks and I was in the hospital for some blood work yesterday. They decided to do a full exam on me and my blood pressure was really high. In uncomfortable situations (doctors offices-hospital) my blood pressure always goes up. I can actually feel it rising when they start to take my BP.  I tried to reassure the doctors and Nurses that my BP is always normal when I take it at home, but it took them hours to believe me. All my blood work was normal, therefore they were not concerned about preeclampsia.  Has anyone had this same issue during labor? I don't want them to force me into a c-section because of my blood pressure, but I know it will be high when they take it. It is so frustrating to have an issue like this and not be able to do anything about it.  Thank you for listening!