PennStatePride,
It is difficult to comment on your question since you first mentioned that the lesion was on the floor of your mouth and a couple statements later you typed "where the palate turns from hard to soft." Well, the palate is composed of two sections the hard and the soft which is on the top (roof) of your mouth. So you've described two anatomically distinct areas.
In either case, any lesion or mass that persists in the oral cavity for more than two weeks requires evaluation by a dentist or Oral and Maxillofacial Surgeon. These provider would be trained to determine if what you have described is part of the "normal" anatomy or something else.
Infections, salivary stones, enlarged glands, lymph nodes, cysts and tumors can all present the same way to patients. So to answer your question directly - Yes, this is a cause of concern until a professional has determined otherwise.
Information contained within this reply is intended solely for general educational purposes and is not intended nor implied to be a medical diagnosis or treatment recommendation. This is not a substitute for professional medical advice relative to your specific medical condition or question. Always seek the advice of your own doctor for medical condition. Only your doctor can provide specific diagnoses and therapies.