It sounds like it's really bugging you, so you should probably talk to her about it. Just simply tell her that you noticed she's started texting you lately and you're curious about it. Maybe you want to ask her if you need to respond and what type of message is okay to bring up via text. Maybe you want her to stop and it would be a good time to practice setting and maintaining your boundaries. I don't think it has to be an uncomfortable conversation, but it's an important one to have.