I have just made Martha Rose Shulman's Tomato Lentil Soup and my lentils are not soft!!!!! She says they're tender in about 30 minutes. Mine were still hard after 30 minutes and they're not exactly soft two hours later!!!!!! Is there anything I can do to save this soup and/or what could be wrong with the lentils? They've been in a tightly sealed jar for about a month.