Has c4 been associated with gynecomastia? if so, how long off c4 is required for regression?

Yes, L-dopa: is one of the ingredients, and that has been known to cause gynecomastia, but there are also many other causes, including marihuana, other drugs, and low testosterone for various reasons. Usually there is regression in breast size in boys in puberty or men with gynecomastia with refeeding syndrome. A good summary may be found at http://www.gynecoma.com/wp-content/post-files/causes-of-gynecomastia.pdf