Assuming that your ignition was turned off prior to detecting the warm coil, you might check to see if you have power going to the coil while the ignition is in the off position. If so, that would indicate a problem with the ignition switch.
If you do have power to the coil all the time, you should also notice considerably shortened life cycles for your points and condensers in addition to quirky battery charge issues.
Tim
Ant wrote:
Yesterday while working on the bug I realized that the coil was quite warm
> (it didn't burn, though) but I neither started the engine nor I had the key
> contact on, is this normal? bad?
>
> Ant