There has to be a bypass spring, but I bet the pump is inside the oil pan. How much pressure does it show? Does the pressure consistently level off at a certain point? If it keeps building pressure and goes way over the factory settings, or worse yet, fluctuates, you have to take a look inside.
If it is stock parts, then you better get that pump out of it and go new. Check for any metal debris while there, and cut open the oil filter to see what gives. Bypasses don't stick on a whim, something is up.