It's much too soon to worry about an issue. A lot of puppy's ears don't stand up at all that young, some do. My pup at that age had one up and one down (see my avatar). They didn't both go up until around 11 weeks and have been up and down ever since as he has been teething. At 5 months old, he has one up and one that is up .. sorta .. it can be a little lazy still.
Xan Varik von Fernheim (born 4/3/13)