I picked up a new/old Model 19 today. It is in near perfect condition....at least externally. I loaded it with snap caps when I got home and it seemed to be fine. Then the trigger started locking up in DA. It locked up about every eighth pull. I put a drop of CLP down the front of the hammer, thoroughly cleaned it, and now it seems to be fine, but I'm still a little concerned. The revolver seemed as smooth as silk when working it SA. What could make it lock up like that? Do you think I should get it looked at or just keep an eye on it?