A psa of 0.8 seems very low, unless they removed almost all your prostate, and I'd guess that without the sample biopsy you would be considered clear. The Gleason 3+4 probably means they're more interested in treatment than if it had been 3+3. After more investigation such as template biopsy or MRI they might find it's very small although it can depend where it's located. Each case is different.
It can also depend on your general health as the operation is considered major.
I've always said I wanted it out asap but mine was near the edge and a 4+3, later found to be 4+4. Afterwards I was told it was a great choice. Near the edge and 4+4 aren't good signs but it had a negative margin which is good.
You might be some way from needing treatment which could increase your treatment options, but I know what you mean about wanting to be clear of it.
Keep us in touch
Peter