The only time I have ever heard noise like that during a shift, and it wasnt in a 4T65E, was when the clutches were worn badly from not being installed correctly and the inner teeth of the clutches were stripping on the splines they engage to. Again this was not on a 4T65E and I have never heard a noise like that in one of these during a shift so not sure what to tell you. I would take it back to the shop and YOU drive the car with there tech and let them here the noise it makes so you can point it out to them. If it shifts fine to you and them they arent going to be in a big rush to rip the trans apart to chase a ghost so to speak.
