Background info: person in context has shown interest in me in person- in other words she seems to be interested.
So what does this mean in your opinion: (mostly asking what the ;) would mean in these cases)
1) I send Christmas wishes and get a reply same to you followed by a winky face emoticon
2) she messages me "safe travels ;)" again with the winky face
3) or when I wish her safe travels she says thank you ;)
4) when we chat and then I say I'm going to sleep (or the other way around) she says goodnight in a sweet way with the winky face emoticon (we don't talk in English so it's a sweeter/ more child like way to say goodnight in our language)
She did not always use the winky face so it's not something she just does normally it switched from occasional :) to more of ;)