I don't want to assume, but this happened with the S1 switch in prime+aux correct? Or the regular run position?
These lines just leak. Time to take the top off, and replace it with something better (I use a Gates hose, off the spool at O Reillys. Other hunt out the OEM Contitech... its been discussed here). No better time to fail then when you are already working on it for something else (though it never feels that way when you are dealing with it). Replace the entire length, plus the T fittings, up top. Easy project, you will see.