Yes. A gritty lens cap can transfer sand to the front of the lens and potentially into your camera bag, where it may spread to other gear.

Best options:

• Use a hand air blower first to remove loose sand.
• If the cap can be disassembled, that is the most effective fix: take it apart, clean each piece, then reassemble.
• Be cautious with water. Some center-pinch caps use metal springs, and moisture can cause rust unless everything is fully dried.

If the cap still feels rough after blowing it out, don’t keep using it on the lens. Repeated contact with trapped grit is not worth the risk of scratching or spreading sand. In that case, replacing the cap is the safest choice.

Compared with carrying the lens uncovered at the beach, a sandy cap is also a real contamination risk. A clean cap is fine; a gritty one is not. If you’re unsure you can fully clean it, stop using that cap until it’s properly cleaned or replaced.