2.1 PSA after Prostate Removal

My father had recently been diagnosed with prostate cancer with a PSA of 7.2.  He had a procedure in Oct 08 using laparoscopic radical prostatectomy. Around 6 weeks after the surgery (Dec 08) his PSA level was 3.5.  He recently got another PSA test in February 09 with a PSA level of 2.1.  I have read articles where the PSA should read less than .2 around this time frame.  The bone scan is negative  prior of surgery and post surgery.  Have there been cases where the PSA levels are high after the surgery but still show a decreasing rate of PSA? What should he be concerned with when it comes to these type of readings?  He also has trouble releasing urine with force and has to use a catheter three times a day. Also his Gleason score was 3
3=6  Your input is greatly appreciated. I'm really concerned about the PSA level test.