Replying to Ex not all that responsive

My ex and I dated for about a year and a half and mutually ended the relationship because we lived in different countries. A few months ago she started seeing someone new and I haven't really talked to her since until a few days ago. I texted her just to see how things were and how she was doing. Just small talk. Nothing on the lines of "I miss you/want to get back together" or asking about her new boyfriend. Just asked her about work, school, life, ect. She just didn't really seem all that responsive, responding with just one word answers and never really asking much about me or tried to keep the convo going. I know she has moved on and I have too, but it just kinda bummed me out that she didn't even want to talk as friends. I've never had a mutually ending relationship before, so maybe she thinks it's weird to be talking with her ex while she is in a new relationship? If we didn't live on different continents and lived near one another, I could see how it may seem weird/inappropriate to be talking with your ex while in a new relationship. But because of the distance, it just doesn't seem like it would be an issue to be talking as friends. For anyone who has been in a similar situation, what are your thoughts?