voiceover heading issue

Hi, I have a question about voiceover. I have a tableview with multiple expandable sections. Even I don't set the sections as header when I scroll the tableview up or down first and last sections are announced as heading.This is the point , if I don't scroll the tableview and click manually to the sections everything goes fine.But after scrolling down and up weirdly the first and last sections are announced as heading.I checked my code and I am sure I don't override it anywhere. May I ask if it is done by apple or if you had a same reported issue ?