is my ex checking up on me?

[.:ant0ni0:.]

Ok, so we pretty much stop talking about two years ago and now she's with somebody else that I know, she's preganant and is due next month and I heard they got married. .. but anyways I posted a pic on my FB last week and her sister liked it and yesterday i posted a status and again her sisters profile like it (sister that I don't have as a friend and nvr really met and she dosent knoe me as well and me and her sis dont have mutual friends, so obiously they looked me up) so I'm curious why would she do it? Why not just do it from her fb and not her sis, I forgot my page is not private. .... should I just ignore it? It seems weird to me that my ex or her sister would do this