当老外刚坐飞机回国时，你可以使用以下几种问候语来表达你的祝福和关心：

希望旅途安全并尽快恢复时差

"I hope you had a safe trip and will recover from your jet lag soon."

祝愿飞行顺利并期待再次见到对方

"I hope you had a safe flight and I look forward to seeing you again soon."

一般性的问候和关心

"How are you？"

"Nice to meet you."

结合飞行安全和归来的祝福

"I hope your flight was smooth and safe, and I wish you a pleasant journey home."

这些问候语既表达了对他旅途安全的关心，又体现了对他的友好和期待再次见面的情感。你可以根据具体情境和你与对方的关系选择合适的问候语。