I believe that was the issue. However, I think the spring for the block was broken. Also, I have heard that firing when decocking is a common problem in P38s
Sig instructors taught us to decock after pulling the gun toward your chest (before angling it down toward your holster), so the muzzle is still pointed downrange.
Some guns did.....that Ruger P85 recall is scary....lots of those guns for sale in used gun sections everywhere......if they have the MKII stamped on the decocker, then they had the factory fix. If not .......then look out!