Might be the string brand, BOB, and they do continue to age even when unused. Concert violinists are lucky if they can get a week out of strings--I tend to either use them til the break, or try to change them once a year. If they funny sounding I will change just that one.

I have noticed that steels last longer than gut or cored strings. The core stretches much faster and won't stay in tune.

We had an old fiddler (70's?) whose parents bought him a Sears/Roebuck fiddle when he was a child in the 1930's. They also bought him a lifetime supply of strings! He was still using the same fiddle (shudder)and old "new" strings when he died. His string life was about 3 songs because the strings were so corroded. We always said a silent "Thank You" when he broke a string because it would take the rest of the gig for him to change it!