Well, yes, but if it was only returned for the safety upgrade, would they have added the property stamp on the top strap? Seems unlikely, and this one was obviously shipped before those marks came into use. The U.S.N.C.P.C. guns were not part of the Navy Contract, which wasn't entered unto until after December 8, 1941. The U.S.N.C.P.C. contract was agreed to nearly a year earlier. So we wouldn't expect those guns to have the Navy mark on the top.
...
Not the Navy, but the US property stamp.
This hypothesis of mine is admittedly based on only one data point which I've presented here before. A pretty persuasive one, though.
Pre-Victory 910507 shipped to the DSC warehouse in a shipment of 100 in January 1942; no stamps were applied to these at the time. When I acquired it, however, it had the US PROPERTY GHD stamp with flaming bomb and the triple P proof. The possibility of a fake can be dismissed because its appearance is absolutely authentic and these marks are in no way value-enhancing.
Since the property mark was only applied to military guns and not before mid-1943, and the triple P proofs, acc. to Pate, not before early 1944, the gun must have returned to the factory for repairs, not refinish (it's still all-original) in 1944, at which time it was in military possession. It was repaired and went through the ordnance inspection, at which time the missing triple P proofs and property marks were applied.
That's what makes me think that if a military gun went through remedial P proofing, it could also be expected to get any missing property stamp. But as I said, just a working hypothesis.
It was most likely among the batch of guns which were, per Pate, transferred from DSC stores to the Navy in early 1942. I had Bill check the SWHF files, but unfortunately he found nothing on this serial.