I get that he's grateful that he ended up with good masters but he reacts to basic kindness like he's never known anything good before, even in his previous life. Maybe he really did have a 100% miserable life back in Japan but it feels like the reactions are pulled from other manga with grateful servants.
I'm not feeling the prior experience of being a free individual. Usually, they rise above in situations like this while still respecting their employers who helped them out.