I had a Vasectomy, and went in for my first semen count and it came back negative, should I go in again?

Ok so I went in today and had a semen count done it was my first one since the vasectomy in the end of July. I got a call that it came back negative (by a computer recording not a human, hate when its a recording). According to the pamphlet the will not give you a clear go ahead till you do a second test which is 4 weeks from today. Has anyone else did the second test, should I still be using condoms or should I take the negative sign and not worry about it.