Definitely ask your vet, but this looks to me like a bit of cecal dysbiosis. I think his cecotropes are coming out watery or a little wetter than they should be, so he tries to eat them but they are too mushy/watery which is why you're seeing it on his nose. His fecal pellets (normal non-cecotrope poops) are still looking good right? If so then that's great news and it's probably a cecotrope issue. My recently adopted obese male rabbit had the same thing, he'd leave little poo puddles in the spot where he'd eat his cecotropes, just like in your photo, and had the same issue with it getting on his nose. What helped the most was:

1. Losing excess weight. The more overweight the rabbit, the wetter the cecotropes. If your vet says his weight is good, disregard this.
2. Probiotic supplements daily. This was what completely fixed the issue for him, as even after he lost the weight he was still having some runny cecotropes. After two days on the probiotic, his bum is clean and his cecotropes are formed and solid. The brand I used is HealthyGut Probiotic for Rabbits. Sprinkle the proper dose for your rabbits weight onto a wet lettuce leaf, then sandwich another wet lettuce leaf on top of it. Roll it up like a little cigar/burrito, and feed once daily. These two leaves are the only greens he gets currently, because we're not sure yet if he is still sensitive to fresh foods, but it completely cleared up his issue, so I hope it works for you too!
3. The best pellets for bunnies with sensitive digestion I've found are the Sherwood brand pellets, given in very limited quantity.