I'm thinking that there is an O-ring there but it slipped down and got pinched between the lid and the inside of the housing.
The good thing is that since the lid is supposed to seal inside with the O-ring; a few little dings on the lid or top if the filter housing should not have an effect on the sealing as long as the lid sits flat.

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84 300D, 82 Volvo 244Gl Diesel