I am by no means a potty expert. I can only tell you the experience I had with mine. When I stuck my pup in the crate, for the first two days there were both kinds in her crate AND she walked around/sat in it. You can imagine my horror. She never did it after that, though. I found the well-known advice to be quite true: pups do not like to sit in their own mess. Who would, though, right?
You just have to make sure the crate fits her comfortably. I've been told when crate training she needs only enough room to go in, turn around and lie comfortably. If you give her much more room than that, then she will go potty in one corner and hang out in another so she doesn't have to touch the mess. If she has too much room, she'll never learn.
Of course, now if I have to leave to go somewhere, I give her a bigger crate with plenty of room and water since I trust her. I'm not sure if this is what others would approve of, but I just like giving her more room and haven't had any problems with her going to the bathroom in her bigger crate. If she did, though, we would immediately go back to the "her size" crate.
I would think one accident isn't a big deal, but if it continues then you should be concerned.
I hope I was at least a little helpful! Hopefully someone else can give a more professional, years-of-experience-with-tons-of-pups opinion.
Oh, while I was typing this thing members who I'm sure know a lot better than I do replied.
