Discoloured wee not in litter tray

Today I would be very grateful for your advice again - and take the occasion to wish you all a very happy and most of all hoppy new year:

My rabbit Onana (born November 18, male, neutered) is a super litter tray user. While his partner Lukaku isn't so keen on his, he uses the tray all the time. Yesterday night, when coming home, however, I noticed small amounts of wee on a plastic house (the rabbits live in my office, they each have a cage, which is always open), which he likes laying and eating on. Later I also noticed some in one of the food bowls, which is highly unusual. To make matters worse, the wee was rather dark in colour, kind of orange. Onana otherwise seems fine, eats, hops and has also made poo and wee in his tray. He doesn't seem to be in pain. This morning there was no more wee elsewhere but in the tray.
What should I do?
Onana is a very easily stressed rabbit, he hates his transport box, he hates car rides and he hates our (very nice) vet. After each vet visit, I have problems to get him back to his normal happy self - and every time I am scared that he could stop eating as happened once before. I therefore would love not to take him to the vet, but just wait and see if it happens again. (I work in that office, so can observe him all day). Is that safe? Or too risky? Is there anything I can do myself to help him if he has some minor ailment with his bladder?
Thank you in advance for any advice and experience.

Happy New Year :wave: The orange colour might be due to food, carrot, dandelions for example. So I wouldn’t be worried about that personally. Weeing outside the litter box could be territorial marking, could be due to a change in litter or position of litter box, or change in environment. Have their enclosures changed at all? Now that he had gone back to his usual good habits I would dry up and clean any areas of urine not in the tray and wipe with 50/50 white vinegar and water to dissuade him from going there. And I’d just wait and see if it happens again.

Thank you very much, Zoobec. I had actually given them each half a carrot on Saturday, which they normally don't eat. The litter boxes and enclosure/rabbit room have not changed, as far as I can see. I just put in a new small edible seagrass house, which both of them used and nibbled on. I will do as you advised and keep him observed. Hopefully I can spare him a vet visit as they are both due for their annual vaccinations anyway, which I dread. My other rabbit Lukaku also doesn't like vet visits, but he is back to normal in no time while Onana is much more sensitive and stays nervous and not eating well for at least a day. Thank you!

I agree with Zoobec. The orange colour is almost certainly due to diet. Because my rabbits have a large variety of forage, their wee is usually of a different colour each day. Similarly, I don't often see any accidents outside of the litter tray, but when I do I clean up and lightly spray vinegar over the spot. I would just observe him for now.

Thank you, Omi! So far he seems happy and normal ...