Hissing often

[PantherYemen]

Hi

My female veiled cham is hissing (letting out air) with open mouth quite often. It's not when I approach her so she's not defencive or aggressive. She does it all by herself all the time. Any idea why? Is it a sign that something is wrong?

 

[PantherYemen]

Just googled it and it seems it can be a sign of pain and discomfort.