Here’s an excellent guide to bunny poop, with great pics: http://imgur.com/a/5N4lD

If it’s the shiny, soft cecotropes you are seeing, his diet might be a bit too rich and/or he’s eating less grass hay than he should. The reason why you often see them in over-weight rabbits is that a fat bunny can’t reach down to eats his cecals like he should, and thus you see the cecals lying about. Same thing goes for old rabbits that have arthritis in their back. In young healthy buns, it’s often a sign of a too rich diet. As long as there are plenty of of the round “hay-poops” too, it’s not a big issue, it’s something you can fix by adding more hay to his diet (bunnies should always have unlimited hay and water 24/7) and possibly adjusting the amount of pellets -although as a rule, very young buns should have unlimited pellets. All buns are individuals though, so you have to find out what diet is best for your particular bun.