In general, would I need to season a meat when making a sauce?
Learning how to season with salt (especially) when cooking is what separates good cooks from those who are not as accomplished.  Yes, you should season the chicken, whether or not is has an accompanying sauce.  With attention and experience you will learn how to adjust that seasoning depending on the seasoning of other ingredients in the final dish.  However, you should season each component to some degree (again, salt specifically...other spices as needed).