peach jam did not preserve well; any ideas?

i canned some peach preserves/jam last august. they were yummy & the canned jars were good until november/december, at least. we just opened another this week. the color had dulled, to a barely yellow-ish brown. the taste diminished, and tasted a bit "off". it did not make us sick. (i ate a slice of bread with it).

i prepared it with the reduced-sugar pectin. i think i added almond extract. any ideas why it didn't keep ? is it the pectin?

thanks,
donna