Sorry if this gets confusing....

Alright, so months and months ago, I kept two males from one of my rats first litters. One of the males stayed with her. They've produced babies many, many times. Siamese dumbos and black self dumbos every time. Nothing out of the ordinary. So it seems as if there aren't any "hidden recessives". The other male went around randomly. The most recent bin (let's call it bin9) he's been in, he's never been in before (however, his dad had, and nothing out of the ordinary was produced), 3 new females for him. Well, I got babies from them and there are two strange ones. Curly whiskers, weird wavy fur....looks like a rex. Neither the male or any of the females are rex though. It's still very young, but it looks different than the hairless ones I've seen.
Could it be one of the other recessive kinky fur and whisker types I've read about? I thought they're really hard to find though??
I don't know, this is all just confusing me seeing as the mom and son have never produced something strange. The dad and bin9 never produced something strange. But then I put the son in bin9 and two weird little things come out.
Can someone please think of an explanation so I don't lose my mind trying.....