I was getting ready for another protune scheduled for tomorrow and was checking everything to make sure everything is in order. Upon checking vacuum lines, I have noticed oil build up inside of coupler which connects two vacuum lines. Realizing that line leads all the way to the boost solenoid, decision was made to take everything apart and inspect the boost control solenoid.
Two hoses directly connected to boost solenoid in fact had visible oil residue, which meant that there must be oil residue inside of boost solenoid.
I used MAF cleaner to flush out any oil inside of boost control solenoid and as expected brownish oily residue came out from one of the nipple.
Haven't pushed my car hard yet, but so far boost builds up smoothly and everything seems fine. You will need to remove stock intake airbox in order to take two 10mm bolts that hold boost solenoid in place.