Inigo may think he's smooth by avoiding the offers of help like that, but apparently not, considering the other mentions it again now. It leaves him a little unsure for a moment.

"I.." His voice trails off, his brain seeking for an excuse before he continues to speak, delivering it. "There's no need to worry about that. I'm always fine." Inigo shakes his head. "I've been through a lot more than what these missions thrown at us, so I never have a hard time."

That last part is definitely a lie - or at least an exaggeration, because even Inigo definitely has hard times. But he's always been better at keeping those to himself than sharing them with anyone, even people who look as familiar as them.