Although tax cuts and regulatory rollbacks this year fueled small-business optimism to hit its highest level in decades, the latest CNBC|SurveyMonkey Small Business Survey, released Monday, reveals that small-business confidence is starting to cool.

After hitting a record high in Q3, the Small Business Confidence index declined from 62 to 59 in the fourth quarter, led by small moves lower in components across the board. This new data from CNBC and SurveyMonkey underscores the idea that while sentiment is at or near record highs, challenges still remain for Main Street.