Hi, I'm stringing with some Prince Premiere Touch I bought about 2 years ago. It's the last few sets in the batch, and I seem to be losing tension very fast. For example, it is a DT of 38 on my ERT300 right off of the machine, and about 12 hours later (with about 1 hour of playing) it is a DT of 30. Normally this string works well for me. Could it have gone 'bad'??