Redness usually means some kind of inflammation. I agree that maybe he should be neutered. Unless of course you have a definite plan to have him as a stud dog, and breed from him. But I know neutering would be the best answer. This kind of thing could keep recurring. I had an entire male dog before. I thought "why should he have his masculinity taken away from him"? "Why interfere with Nature"? And all those things. He fathered (wanted) puppies. I was proud of him.
Then when he was older -yet still very well and fit apparently and full of life and energy, he got diagnosed with prostate cancer that was so advanced he had to be put to sleep. I asked the vet was there anything I could have done to have prevented that. He said if I'd had him neutered when he was younger, he may well have lived more years.
I have no idea, but you might want to consider having them removed. It sounds like he's old enough to be neutered.