When the fingers massage the palm or the fingers are interlaced together then gently rub up and down as the fingers stroke the inside of the other indicate a person who is in doubt, has low confidence, or is experiencing stress. As tension escalates the gesture will move from palm stroking into more rigorous interlaced finger stroking making the two a progression of intensity. Thus while palm stroking is due to mild doubt or slight confidence issues, interlaced fingers that rub up and down is to do a higher level of anxiety.
Both gestures are excellent examples of pacifying behaviours meant to sooth underlying emotional discomfort. As conversations intensify watch for increases in soothing body language revealing the underlying anxiety.