The moment the ignition keeps ticking continuously, too much moisture has most likely gotten under the knob panel. This can be caused by overcooking or cleaning. The moisture can then come into contact with the spark switch, causing the spark transformer to receive a signal and then start making a ticking noise.
This is not dangerous, as the thermal protection prevents the release of gas. With a gas hob, we advise you to turn on the oven(s) so that it gets warm and the moisture can evaporate, after which the ticking will stop. With a hob, pull the plug out of the socket and let the appliance dry. You can still use the hob by lighting it with a match. Depending on the humidity, the drying process will take time. As the spark ignition dries, the ticking noise will diminish.