The same thing happened to me last month. I went for my 2 year follow up at my surgeons office 2 weeks ago and they said if it goes to 0.2 immediately go for a recheck then call the office. For now, they said not to be concerned. They have told me all along to wait for 2 readings of 0.2 before doing anything further.
It happened in January also then went back to undetectable.
Good luck to both of us!
Bill from Florida
Age - 63
Feb. 2012 - PSA 18.5 Biopsy 4/27/12
Positive 10 of 12 cores, Gleason 6 then
Da Vinci Surgery 07/17/12, Dr. Vipul Patel
EPE, positive margins, Gleason 3+4=7, involving 50% of gland, prostate weight 57 g. Stage pT3a, Lymph node involvement: 0/4
All post-op PSA tests through 10/15/13 undetectable <0.1
PSA 1/15/14 0.1, 4/1/14 - <0.1, 6/24 - 0.1
AUS AMS 800 installed 4/11/14 finally dry