The watch definitely looks authentic, but aside from integrated bracelets, bracelets can be pretty easily swapped, and many people do this as styles and personal tastes change. I’ve seen plenty of vintage Rolexes, Vacheron Constantins, and Pateks with aftermarket bracelets. Often these are custom work, done by a local jeweler, and may be designs completely unlike anything the manufacturer offered, or they may be similar to an original bracelet that was offered a few years later, and so on. So, it’s possible the bracelet was a high quality style update, and not original, but looking at it closely will help determine that. Here are some good photos of a similar era Rolex Date with an original mesh bracelet that might help you determine for yourself if the bracelet is original: Rolex Date on original mesh bracelet.