Change in Urine Color

Question
I have a neutered male rabbit I have owned for about five years. Yesterday, I
noticed some red in the cage he shares with two other rabbits. I didn't think
much of it, because all of my rabbits are litter-trained and it didn't seem like
urine. When I took the three out for playtime, Honey hopped on my carpet
and peed. I put a towel on top of it, but when i took it off, I noticed the pee
was a very dark orange-red. He urinated shortly after and it was the same
color. That night, I put Honey in a separate cage from the other rabbits, and
he went when I set him down. This time his pee was normal yellow.
I took him out for playtime this morning, apart from Coco and Oreo.
he didn't urinate, but when I put him back in his separate cage, he went and
his wee was orange. I don't know what this means. Is Honey sick?

Answer
Most of the time, this color change isn't a problem at all.  Is there anything at all that has changed in his diet?  Or does he get food like carrots?

Often urine color is related to something they've eaten.  And the color change is something that comes and goes.

This article gives a good synopsis of these color changes:
http://www.rabbit.org/journal/3-1/red-urine.html

This site gives some more example of possible causes:
http://www.peteducation.com/article.cfm?cls=18&cat=1803&articleid=2839

Usually, this is no big deal.  If you were ever to see something that looked like blood, then you'd want to have a vet check it out.

He probably isn't sick, this is just something you can watch, and if he starts to act sick, no eating or drinking as much, or acts like he's in pain.  Then you can take him into a vet