I'm gonna guess this is a typo? You went from .005 to .001 in 2 mos? That's a decrease.

If it went from .005 to .010 in that time, I'm not sure about worried, but it's something your dr is going to discuss with you. Maybe consider some type of ongoing treatment if it continues.

One of the statements my radiation oncologist made to me was that rate of doubling in those very low numbers such as you're in is not nearly as troubling as in the higher numbers, i.e. 2 going to 4 etc.

I went from .039 to .091 and it indicated going for radiation treatments and ADT. Last one is tomorrow. With your numbers being so low to start with, it's likely less significant, but, there are others here who have studied this a great deal more than I. Hopefully someone will have something more definitive for you soon.