A little play in exterior parts does not automatically mean image quality is affected. On many lenses, the optical groups are supported separately and stay aligned even if the focus ring or some barrel parts become slightly loose.

What matters is whether the glass elements are moving out of alignment. If they are, you may see softness, uneven sharpness across the frame, or focus problems. If only plastic barrel parts or the focus ring are loose, image quality may remain normal, but usability, weather sealing, and long-term reliability can still be affected.

There is also some risk that loose internal/mechanical parts could eventually damage fragile components inside the lens.

If your photos still look normal, the lens may be usable for now, but monitor it for changes in sharpness, focus accuracy, zoom creep, or increased wobble. Because it’s a weather-resistant lens and sealing may be compromised, it would be sensible to contact Pentax/service support or have the lens inspected, especially if the looseness appeared suddenly or gets worse.