Haha that's cute!!I don't think anyone knows for sure whether or not they can see color, so it's probably not that. But it probably "smells" different or is a different shape so she has to check it out.
I use coconut bedding for my baby and every time I change it (and every time I mist) she always has to explore the entire tank and seems very interested in the bedding, sniffing it etc. Their tank is their "territory" so they always have to know what's going on within it