Sudden tension change!

I have had my Amara 2+ years and have quilted with the same fabric, thread and tension settings.  I was almost finished w/a large lap quilt 3/4 done and all of the sudden I am getting eyelashes on the back.  Nothing changed from the 3/4 done to the final quarter. I called my sales person and asked what happened.  I always use the top tension setting between 28 and 34 w/o any problems.  He told me that the settings are not reliable and to discontinue using them. Just to adjust tension by using.  My question is:  why would you design a program to help w/the tension if it's not to be used?  I also did some tension adjusting and am finally able to quilt.  New setting is 80! What caused the big change?  Hope this makes sense if not, my number is 805 801 5361 Glenda