Utterly unimportant and completely normal. It’s necessary to ensure that the brakes release cleanly. Provided the pads can’t actually slide out of the caliper it’s fine.
They take the play out on road cars to stop the rattle and the inevitable complaints that “something is wrong with my car, there’s a clunk when I put the brakes on at slow speed” but the result is brakes that drag faintly all the time. Track car brakes run a little play like bike brakes for free operation and to allow the pads to expand when they are hot on the assumption that the driver is clued up enough to know what the clunk is.
