I have flown with Air Asia several times and with other airlines that have weight limits for hand luggage.
Air Asia has never weighed my bag, although I have seen others go through this. Sometimes it happens.
My impression is that I would say that it really depends on two factors.
1: How full is the plane. If they are waiting for a full flight, then they will be actively looking for the baggage to force it into the hold.
2: How big and heavy your bag looks If you have a small bag with a weight of 30 kg and you are strong enough to carry it as if it were nothing, it is much less likely to get caught than someone with a huge backpack who are struggling to carry, but barely enough. The weight limit.
The general advice I would say is that you prepare for the worst and keep your bag close to the weight limit. However, if it is inevitable that your bag be heavy, try to hide this fact and make it look as light as possible; Also, do your best to stay out of the staff members who weigh the bags!
I would say that this is a case of weighing bags is something that they reserve the right to do if they wish (for example, if the plane is full) but it is not their usual practice.