I've noticed a few times now, in different quests and campaign.

Ice Wyrm sometimes get a special "Each attack this turn gets +2 surges".

But Ice Wyrm don't have a single surge use, so it's kind of irrelevant.

It's a generic buff for 2 monster groups methinks. I've seen ettins get it, with only 1 surge ability, elementals, etc.

It is a bug. They will exclude abilities like that for other monsters where appropriate. Unfortunately as a general rule activations on monsters from H&M packs are not as good as those from expansions.

The generic activations are not always useless though. Sometimes a surge can be required to not miss a hero.