This happens to me when things are dry. My nose explodes. I'm not sure I've known anyone to valsalva "too hard". I think most people tend not to brace hard enough.
Your first two reps were your best. 3 and 5 you started rocking back just slightly and opening with the chest to break the bar off the ground instead of pushing the floor away. See your hips slightly drop and the bar moves forward a little as it breaks off the ground on 3 and 5?
Carry on.