I just picked up my bass from getting a setup and I noticed that it seems like they only replaced the stock Fender strings on my E string, and none of the others. I called the place and was told that he saw that the E was darker than the rest, but there are indeed all my Rotosounds because they had red threading on both ends. Has any other RS guys ever came across this? I've been playing them for 4 years now and have never seen it. Is the tech correct or is he talking his way out of a mistake?