the carry-on weight limit is not often enforced, and when it is, its usually done during check-in where they ask you to weigh your bags. at the gate, its more common with discount carrier (for obv reasons).

specifically with SAS i've never seen a bag scrutinized for weight. if you carry something that *looks* heavy (e.g. its overstuffed), you might be stuffed. otherwise, shouldnt be a prob.