Visitor Visa - B2

I was an undergrad in the US and worked on OPT for a year before moving to Canada. I applied for a B2 visa to visit some of my friends. I had my appointment at 8 am today; however, the people were taken in on a first-come, first-serve basis. The security guards were extremely rude while you were already in an intimidating atmosphere. Once I got in, the DS-160, passport and the confirmation email hard copy were checked, and fingerprints were taken before the interview line. As I approached the interviewer, the first question was about the purpose of the visit. I answered that I was visiting some of my friends; I did my studies and previously worked on OPT in the US. The officer said he would pull up my OPT info on his computer and ask about my profession. Once I told him about my job, he said the visa was approved and the passport would be mailed within five business days. Overall, the people working inside the consulate were very kind, and the process was smooth. I wish they would train the security guards on professionalism and proper etiquette for dealing with applicants.