It's not normal in the way that a therapist shouldn't voice assumptions like this. T can't possibly know why you were upset, unless you say it yourself. Maybe that person reminds you of your mom, maybe of you aunt, or maybe of that girl you knew in 4th grade. It's your emotions, and only you can say why you reacted the way you did. Of course, therapist can be right with this "maybe it's your mom" thing, but they can also be wrong. Sometimes it's not a big deal, but some clients (who want to be "good" clients, to please a therapist) may adopt T's thoughts as their own, and then therapy is easily sidetracked.