Worried

I had an RRP about 3 and a half years ago and have had a PSA of less than .1 since. This week I went to have my annual checkup and was told that my PSA is now .3. I was told to have another PSA check in three months and if it's still high to consult with a radiologist to have radiation therepy. I'm 53, in very good health and have recently had a bowel resection and temporary colostomy due to diverticulitis which has been reversed. I'm wondering if my recent surgery could affect my PSA reading and if not, how serious is this reoccurance? What am I facing and how serious is this? I had some spread beyond the prostate but the doctor said he thought he was able to remove it all. My lymph nodes were clear. I had no symptoms prior to my surgery. I would appreciate any info on this. Thanks.