There are other things that can raise the PSA: prostatitis (infection), sex, DRE (Digital Rectal Exam).
If those don't apply to you then you should get the biopsy now. It will never be easier.
My first PSA was 17.8. I was in perfect health and did not feel a thing. The doc started me on antibiotics just in case it was prostatitis. A few weeks later my PSA was 22+ and the biopsy was scheduled. Read my stats.
I hope the day before your PSA test was spent having a hot, wild time in bed with all kinds of kinky devices and rough partners. That would be the best reason to have an elevated PSA. Otherwise.... get the biopsy.
Age: 59, Mar 36 yrs, 56 dx, PSA: 4/09 17.8, 6/09 23.2
Biopsy: 6/09 7 of 12 Pos, 20-70%, Gleason 4+3 Bone, CT Neg
DaVinci RP: 7/09, U of Roch Med Ctr
Path Rpt: Glsn 3+4, pT3aNOMx, 56g, Tumor 2.5x1.8 cm both lobes and apex
EPE present, PNI extensive, Sem Ves, Vas def clear, Lymph 0/13
Incont: 200ml/day ED: Trimix
Post Surg PSA: 10/09 .04, 7/10 <0.01, 7/11 <0.01, 1/12 <0.02
AdV Sling 1/10/11 Dry