Any ideas why gerbils might have 'greasy' fur?

[rosealbie]

They are about 7 weeks old and we have only had them a week. Their fur looks greasy and i'm worried they might be unwell. They seem to be eating OK and quite lively but look a bit like they have been rubbed all over.

i know hamsters have some sort of gland that makes their fur look greasy on the sides. could it be something like that? would they be reaching adulthood at 7 weeks?
I had a ex who had 3 gerbils but one ate the other two . dear leetle rodents.

Oh no, I hope they don't eat each other!

I guess it could be that but it's all over their body.

what are you keeping them in? I had some in a tank when I was younger and they had this, I think it might have been slight humidity?! They seemed to improve when they went into a cage (although the cage didn't last long!), but it might be a gland thing as both mine were males...

They are in a gerbilarium, so half cage/half tank. They are both female.