Green-Thighed Frog in Lancefield???

Green-Thighed Frog in Lancefield??? Today after work, we found one dark chocolate frog swimming in one of our frog-friendly buckets. According to it's lime-green hind legs with the black spots, we think it's a Green-Thighed Frog. But question is this frogs are restricted from northeast NSW to south-east QLD. Why are they here in Lancefield??? They are so beautiful! I can't stop looking at it.