That's not quite proof of stable.
Folding will honestly push your system to the limits, and it honestly is probably the best "benching" tool.
I've had an OC look quite stable. 150 passes of Intel Burn Test with max memory, and my computer crashed after 1.5 days of folding.
I've been reading up on voltages a lot lately, as my processor requires extreme numbers to reach a stable 4.2ghz, but from what I've found, 24/7 use with high voltages (1.4+) is doable, without damage to the chip. This is of course, as long as temperatures are kept in check. From the sounds of it, yours are, so there is no need to worry.
But I am going to redo my whole OC tonight I think, group up no saved setting and see what I can get.