I'm not a longarmer, but if she is IMPLYING that the quilts are HER work, then I would speak to her about it. Especially if people are signing her guestbook stating they like "her" quilts and she's not correcting them by saying they aren't hers.
Most quilt shops I have visited on and offline have had the name of the maker on the quilt and have given reference to them.
So, if you talk to her and she's not willing to do as you ask, then I wouldn't go back to her.
That's my opinion.......