I personally would do neither one of those, Arashi. I would not ignore it, nor would I make a huge display of it. I would simply casually mention, without going into details, that I had been learning about PTSD, and then let her decide whether she wants to speak more about it or not. That way you are giving her the option of how much information she wants to absorb at the moment. Additionally, she may very well know the information already, in which case she may turn on you and accuse you of being pushy or patronizing.

One thing my husband does with Evie, and you may not have a good an opportunity as you don't live with your girlfriend, however - he prints out articles from the forum here, that he believes pertain to Evie's current state of mind. He then leaves the articles where she will find them, usually at the breakfast table. It works with Evie, as she can read the information as her leisure and not feel pressured to talk before she's ready.