You had helped them escape the Marines a couple months back, you disappeared before Luffy could ask you to join his crew, you now ran into them again. They're on an island, their boat anchored on the shoreline

Luffy: He see's you Hey! It's the guy who helped us!

Nami: Hm? She looks over Oh! Hello again. She smiles and waves

Zoro: He gives you a nod of respect

Sanji, Franky, Brook, Robin, Usopp and Chopper say hi and wave

Jinbe: Hello. Thank you for your previous help.