Did you know that an Australian Shepherd ears can change position quite a bit until around 5 or 6 months old? I have an aussie-poodle mix and I figured her ears would lie flat like a poodle. Then at about 10 weeks old, her one ear pricked up and sort of folded forward (very cute) followed by the other. I did some research and found out that this is common for an Australian Shepherd. And apparently the final ear can be lie flat, be a semi-prick (up but folded forward a bit), a full prick (straight up), a "rose" (sort of up and folded back) or even a combo - one ear up, one down, etc. Today at 4 months her ears have come down a bit and are what I would guess to be "rose" but she still has a couple months to go.
I understand this can occur in certain other breeds, like the Border Collie.