I can't tell just by looking at the spool in the store, it would be nice to have a born on date huh? Not sure of the line you use but I had the same problem with Trilene 13 years ago and have not used it since. I was convinced it must be my knots or treatment of the line on the reels but it seems it was just bad line and it happened alot not just one or two times over a period of a season.