98 Dodge Ram 1500 4X4

There is a rubber boot that covers the area where the transfer case and drive shaft connect.

There is a very small hole in this boot (I think it's suppose to be there). And I have a real small leak from that.

I checked the transfer case and it's full - slightly overfull actually.

Could this be some type of overflow, or do I have a leak. If a leak, what would it be?

Thanks