Twisting stems could be a symptom of herbicide exposure or a virus. If you did not use any type of herbicide on your property, it is still possible for plants to be exposed to "herbicide drift" from nearby farms or yards where herbicide applications are used. Some plants are more susceptible than others to growth-regulators that are used in some types of pesticides. If an exposure was minimal, the plant should eventually grow out of the damage. There really isn't anything you can do, other than normal good plant care practices such as watering during dry periods. A virus can also cause twisting stems, but your plant doesn't appear to show other indicators of a virus (such as unusual color patterns in the leaves).

Christa