Hi again Jenny,
If you're neurological clinical assessment has found 'ankle clonus' as well, you're clinical assessment is not actually normal so the medical causes become even more limited.....ankle clonus is an extreme type of hyperreflexia, generally 5+ beat clonus is abnormal, it's an upper motor neuron sign and is associated with spinal cord lesions and or spinal injuries, clonus is a clinical sign of certain neurological conditions and MS is one of them.
I personally have ankle clonus, not sure i'd say it's something to be concerned about other than it being additional proof that something neurological is wrong, you can't really do much of anything about if that's what your meaning. It's not actually uncommon to be unaware of it, certain things can trigger the leg to bounce though but you can stop it with pressure.
Spasticity is often an issue with clonus, so stretching and medication can help with muscle tone that's too tight and causing add on issues but keep in mind that not everyone with ankle clonus will also experience spasticity, so as the saying goes 'don't borrow trouble'....
Hope that helps......JJ