Hello claier,

I believe , but not certain without doing additional research, that H cinera will have some dorsal color changes depending on their environment?
Many can vary in color ; yellow-green and even a light brown/redish to green . I believe I have read that the dorsum can have small golden spots on top of their more common green coloring. If the frogs is eating, doesn't have diarrhea, and it acting "normal" ....well then everything is probably fine.

Keep a watchful eye
Keep us posted.

Take photos often You might start a FF photo album (?) of the coloration changes that take place as all members will enjoy reading the information gained by your observations.