Lane A check question

When I do the run-up and switch off the Lane B nothing happens apart from a slight RPM drop. If I switch off Lane A I notice a very short hesitation and hear a click. As if it takes a fraction of a second before the Lane B takes over? I get the impression that the RPM does not drop, but actually increases a little bit. I don't see any faults popping up. But I cannot remember having noticed this very sort hesitation before. Is this 'normal' or something to worry about?