I have no idea if it is polyploid or not, a test only costs $10-$50.
Polyploids are not so stable, the only way to know is to test it. And yes a Tetraploid or Triploid can revert to Diploid. If you self a diploid it the progeny is a diploid, if you self a Tetraploid it will be a Tetraploid, if you self a Triploid it remains a triploid. If you transform a Tetraploid from a girl to a male for a pollen source, and use the pollen on a diploid female the resulting seeds will be Triploid, but not all the plants will be 100% Triploid, some plants will have mixes of polyploid and diploid, they need to be tested for confirmation.
-SamS
Thanks a lot brother, I will have to consider testing her then. That is quite cheap to satisfy my curiosity. This is very interesting.