Coolant leak after thermostat hosing

I recently replaced my thermostat, water pump and radiator now I have what I believe to be a leak at the housing the old thermostat hosing had some pitting on the sealing surface thought it would be fine now I appear to have a leak has anyone had this issue before.thought it might have been the o ring grease ,I used melting but not shure.

 

that does not look like a leak? looks like an oil stain, pressure test it and see if you see actual coolant, maybe recheck bolt torque

 

I pulled it off and tried to get a new housing but Toyota gave me the wrong one so I resealed the old housing. I will see if it holds.