Yes. it was almost certainly the sear catching the half-cock. This shows that you have excellent trigger control, Gibbs505, and that the 2-stage trigger has been ground down to a single-stage pull. This is not an unreasonable modification to perform on the smelly, but can have that annoying side-effect.

If the trigger is still 2-stage, you may have a more serious problem. Either way, replacing the cocking-piece is a simple job which will almost certainly fix the trigger.