Having a lit smoker at hand is always a good idea; Murphy’s Law tells us that if we have it, we won’t need it. However, if we fail to have it on hand, we may need it. The unexpected is normal in beekeeping; the bees don’t read the manuals that we beekeepers do.
Bees in the spring, particularly in small hives or nucs are so focused on spring buildup that they often hardly seem to notice the beekeeper’s invasion of their home. They may need minimal distraction, if any. This is a good time to try a spray bottle of water, perhaps with a few drops of peppermint oil in it, or peppermint oil on bare hands, or simply working without gloves, especially not the ill-fitting clumsy leather ones. Spraying sugar water is recommended on the internet but might set off robbing, particularly later in the season during summer dearth.
Warning: other mints are bee attractants; apparently peppermint masks alarm odors.