Lump and third buttonhole

The CNP was in today. I showed her a noticeable “lump” or bulge in the vein in my arm with the fistula (above where they put the buttonholes). She didn't seem very concerned – although both my husband and I are. I thought I ought to see the vascular surgeon who created the fistula; CNP felt that they could just keep an eye on it. I am still not convinced. Does that sound right?

However, when she was looking at my arm, she suggested that we start a third buttonhole. I have never heard of that. Is that common? I am not having problems with the buttonholes I have. CNP said it would be as a backup in case the tech had a problem using one of the other two. The tech would rotate among the three. I thought the whole idea of the buttonhole was that you wouldn't have new insertion sites all the time and the two access spots would provide easy entry. Does having a third access make sense?

Could these two (lump and third buttonhole) be related?