We've just had a wooden floor laid at home (by professionals), and now I'm
wondering how well the job has been done, and I'm hoping some of the experts
here will be able to advise me.

It's a Bruce hardwood, engineered board, floating floor, made up of 5"
planks. Most of the planks fit together perfectly (there is no groove), but
at the ends of some of the planks there is a gap, wide enough to fit your
thumbnail in.

My question is, should I be worried over these gaps, will they let
moisture/grit in etc., or is it perfectly normal (and presumably with
shrinkage/expansion gaps will change anyway)?