if the cabin is dry
the water pump weep hole or gaskets are not leaking
the heater hoses are not leaking and the coolant pipe from the water pump to the heater hose in back of the head

then look for discoloration behind the exhaust manifold where the head meets the block.

if you find it then you have a degraded head gasket which is living on borrow time. i just replaced one on my own 940 which had been leaking for almost 2 years.
do not let my laziness to fix my own car persuade you, should you find the leak behind the exhaust manifold, you have 2 years before it get real.

you have not mentioned mileage of the car. mine was 250k when it started leaking and 290 when i got around to it.

i find a head gasket seldom lasts beyond 250-300k miles from simple old age and sour coolant. sometimes MUCH less than that.

Forgot to mention look for a weeping water pump.

Check for leaks at the rear of the engine, heater hoses. Does it smell like coolant inside the car? Any wet carpets? Check for leak at the heater control valve and also heater core ( I hope not, big job). You could still have a small crack at either the upper or lower neck of your new radiator that will only leak when the car gets hot. Check for loose clamps around hoses. And last but not least is a failing head gasket. Open the overflow, does it smell like exhaust fumes?