How long were you in China? If less than 1 year then I believe you do not need to get on from there.
Here is what the state department FAM states:
9 FAM 42.65 N4.1 From Country of Current
Residence or Country of Nationality (Canada)
(TL:VISA-185; 02-26-1999)
An applicant must present a police certificate, if obtainable, from his or her
country of current residence or nationality, if residence in such country
exceeds six months
9 FAM 42.65 N4.2 From Country of Previous
Residence (China)
(TL:VISA-185; 02-26-1999)
Police certificates are required from countries of previous residence, if
residence there was for more than one year
http://foia.state.gov/masterdocs/09FAM/0942065N.PDFhttp://travel.state.gov/visa/reciprocity/C...der/C/China.htm