I had a bathroom delta faucet replaced with a hansgrohe
logis loop faucet. There is now a slight
leak where the metal of the faucet drain joins the plastic drain. The leak doesn't start until
approximately 30 minutes after water has been run and lasts for about 10 minutes. It is leaking from above the plastic
fitting joining the two pipes.

Why does it take 30 minutes for the leak to start? What should be done to fix the leak? Thank you for your help.