K so you aren't the first one to get creeped out by this. Plenty of people have seen this too, but no actual relationship has been found yet. So if there is a link, it's all speculation with no hard evidence yet.
With the ghost girl,
>Lumiose City Ghost Girl: Bring Rotom to the floor in Tuesdays to obtain Rare Candy.
TMV Station: Note Behind the Board at the Back: Currently unsolved.
Marrilands
>On the second floor of the Fighting Dojo, a Hex Maniac will appear, say "No, you're not the one," and float away. The purpose of this in-game event, if there is one, is not known yet.
Bulbapedia
>For added creepypasta elements, go to Lumiose Station and read the signpost at the back end from the reverse side.
Neoseeker
>If you got to the lumiose station, and go to the second TMV timetable (the back bords) got behined it and press a on its back theres something writen on it. It should say '' I'm going to go for help wait in the usual place'' it might be connected with the hex girl
GameFAQ
Etc. etc. The general conception seems to be that these may or may not be linked to a future event Nintendo plans on releasing, so stay tuned I suppose.
And tips are just some random feature, they don't have any actual effect. If you actually get cursed, Pika isn't phat.