If it's a LOT of blood I'd be concerned (a lot as in the urine looks like blood and not at all like urine). Jimgreg is right, if it's pinkish urine it's probably from a stone passing. I've had stones go where I had no pain but blood present, used a strainer and I definitley had stones, they were just so small they didn't hurt. On the flip side of that, it might not be a stone at all, there could be an infection that's causing the urinary tract to bleed. In that case he may want to go to the doc, if only to get a urine test to check for infection. I've had two infections that the docs described as "raging" with a temperature of 97.5, so depending on how his temperature functions, that's not always a good indicator of infection.
Good Luck!!
when stones are passed..theres going to be excess blood..as long as its not a on going problem..i doubt if the kidney is bleeding..its the urethra from witch the stone travel my opiun only!!!!!!!