Being too quiet?

Being quiet isn't a bad thing. I know someone who's had complaints from her patients that she talks too much :) - but your instructor probably feels comfortable when s/he's hearing regular verbal feedback from her students. Just be sure to ask a few questions per session. That way she gets the verbal assurance that you're keeping up with what she's saying and you won't have to worry about having her hold it against you when it comes to your grade.

Maybe she just wanted you to talk to the patients you're working with more to establish a better relationship? If its not affecting your work and your patients aren't complaining that they don't feel informed enough about what you're doing, I don't think you need to worry about it.

I'm pretty quiet myself, and some people take it for coldness unfortunately. As long as you're friendly enough to the patients during clinicals I think you should be fine.