Marty, it sounds like your girlfriend probably did orgasm. Women are all completely different, but in my experience, most women who masturbate regularly are experts at keeping quiet - I usually make a lot of noise when I come, I think the sounds, sexual moans and gasps are a real turn on...but growing up, and trying to keep it somewhat of a secret when I shared a room with my sister, I learned to be very discreet.
Some women are just quiet anyway, for whatever reason, although I've found a lot of women who are quiet about sex, are a little shy or self-conscious. But everyone's response is different, and equally as wonderful.
I can still be as loud or as quiet as I feel like, and no one has to make any noise..although some find it hard to help it, me included if someone else is touching me, I can get quite noisy. When someone else masturbates me, it's a different feeling altogether that when I do it - and I find when someone rubs my clit in a certain way, I shake when I come - sometimes quite violently, it's a lot more of an intense and focused feeling than when I rub myself, or slide my own fingers into my pussy.
Try getting her to talk about it, tell you when she's about to come. Or maybe she's a little shy, and finds it hard to talk about, or to let go completely. Maybe she could squeeze your hand when she orgasms or something easier. I know I love to know when whoever I'm with comes..it's amazing to know that I could give someone that much pleasure.