A lot of manufacturers increased cold tyre pressures around this time to reduce emissions and improve fuel economy when the WLTP (Worldwide Harmonised Light Vehicle Test Procedure) was introduced to measure miles-per-gallon. Previously engines were bench-tested to get economy data. The newer procedure simulates real-world driving conditions and higher tyre pressures give lower rolling resistance. If you prefer the softer ride of 33psi it's a decision you take at your own risk as 38psi is the manufacturer's quoted tyre pressure for the model.