Welcome back:
That's good news. Honestly, the radiator caps are designed to release pressure at a certain point and allow coolant to return to the overflow. It is very possible that is wasn't installed fully or the cap itself is just bad.
Since a new cap is inexpensive, I would recommend replacing it. Chances are that is the issue.
Please feel free to let me know if you have other questions regarding this issue.
Take care,
Joe
Tuesday, April 30th, 2019 AT 7:05 PM