It's usually a good sign when the officer takes the I-94.
No need to be apprehensive, if you feel the interview went well then wait for the outcome, if any more documents are needed you will be notified.
I would concur with the previous answer. More likely than not, you will receive an approval in the mail. If the you don't receive any notice in another couple of months, then you should inquire.
Best of luck.
Verdin Law Firm