no flame trap per se, but you still have the crankcase ventilation plumbing to keep an eye on. Turbo or non, it can and will get plugged, especially if the oil change interval of 5k miles with dino oil, was followed. 5k is too much for dino oil, regardless of whether volvo recommends that. They recommended it to keep the cost of ownership down. Get the crankcase plumbing checked out and you will probably find the reason for the pressure. Also, if the gasket looks fine, looks can be deceiving. They become inflexible without showing any other signs of degradation (i.e. cracking). Change the gasket with every other oil change.

BB