The image alongside shows an example where the U.V. strip does not come to the edge of the sail when furled.
When it comes to the end of the season (or when the sail is down) separate the sail from the U.V strip in your hands and try to tear it as if you are opening a crisp packet. If it tears easily then you will need to get a quote for an new UV strip.
If there is no U.V strip, the strip is not wide enough or the U.V strip tears it might be an idea to phone your local Ullman sails loft.