Gum Gum and Kyborg, Perception Checks

Gum Gum was on first watch and Kyborg on second watch as the party takes a long rest before starting their journey to Broomafune. I guess Gum Gum and Kyborg, both of you make me perception checks. What does that mean? He just decides when he has advantage on deck saving throws against effects that you can see. So the perception checks were 12 for Gum Gum and 17 for Kyborg. The rest goes uneventfully. You all don't notice anything at all out of the ordinary during your watch. And everyone wakes up refreshed and ready for a new day.