Hi Loren, Welcome to the forum ..Yay!! another New Zealand-er.

These frogs do change colour. The fact you have had him/her for 3 weeks and also have move him /her in that time would suggest to me that your frog is under stress and needs time to adjust to the new environment. Make sure you have plenty of hiding places for Freddo which will make him feel safe and relax more. You say your frog is eating well so that another good reason no to be alarmed. I would also suggest monitoring the temperature and make sure its suitable. If your shutting the curtains does the enclosure have light? Please if you haven't already check out the care article...Great to have you here .
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