Vapor Coming From Front Vent

I have a Quick Fuel carb on my 440. Today I had the air cleaner off doing some work under the hood and while the engine was running I saw vapor coming out of the front bowl vent. The fuel level while the engine is running is right in the middle of the sight glass. The engine seems to run OK, but the major issue I have is that after it sits overnight there is no fuel showing in the sight glass. Guessing it's boiling off.

Any thoughts?