To a certain extent yes you can have 'controlled' BP and still have proteinuria due to PE.
There is increasing evidence to show that women who preset with new, clinically significant protein (2+) but have normal BPs should be paid close attention to. This is because for many women new proteinuria is a pre-cursor or the first symptom of PE.
This is also why it is mentioned in its own right as part of PRECOG.
If new & clinically significant protein is present then research suggests PE will develop within 2 weeks..
I hope this helps.
Every Woman is entitled to understand what happened in her pregnancy when pre eclampsia strikes. I hope to be able to support that process.