I would definitely congratulate her.

My T didn't have a maiden vs married name for me to discover (T was a he), but I found an online picture of him being honored by a national organization and congratulated him for it, then asked him about his experience. He was not surprised or uncomfortable that I found this picture, and we discussed his service/ accomplishment.

Hope you can talk to her about this, although it seems appropriate either way.

edit: Just read other replies. If your T knows you for 4 years, she already knows you are not a stalker, right? I hope you don't stress too much about that.
I told my new T on the 1st or 2nd session that I found him by reading his published work I found online. He wasn't scared but seemed interested that I wanted to talk about the ideas in his research.

It might turn out to be a nice moment of sharing between you and your T - sometimes talking about things other than trauma and problems and whatnots gives you a nice break and fosters the bond.