It always worries me when someone says their seahorses and (whatever fish) are getting along fine.
How long have they been together? What species, color and sex is/are your seahorse? Are your clownfish an actual pair, or just 2 fish?
My gut feeling is that this may not be an ideal setup for your horse(s). A mated pair of clownfish can become extremely territorial. Also, if you have a male/female pair of seahorses, don't expect to ever see any babies because the clownfish will eat them as they are born. Both seahorses and mandarins love pods, and will eat them as much as they can, for as long as they can. If they eat them all, even tho your horses are bowl fed, the mandarin will starve.
In short, Yes, I still think there may be a problem. Most people keep seahorses in a species only tank for a reason. That is because there are so many problems that may arise when you start adding other fishes, even those that are supposedly seahorse safe.
Could you post a little more about your tank and occupants?