Yes, very likely there has been some pressure built up in the lines and you cannot push hard enough to move that tip button back in the male end.
Wrap with a rag, and press or tap the tip against something hard, like steel, and the oil will squirt out (so be aware of that sudden squirt of oil).
That or loosen a connection in the line of the attachment to drain some oil and relieve the pressure.
This happens when the lines warm up in the sun, and the oil expands building some pressure. Doesn't seem to take much either.