I agree, if it functions fine for its intended purpose 100% of the time, then it is good. If it hangs up occasionally, then I would say the problem still exists in which case, sending it in is your best option.Still may send the gun in since one chamber is about 0.97 mm (~0.38") and the others are about 10.0 mm (~0.394"). My Taurus .357 Magnum has all chambers around 0.97.
So it appears that the 340 PD has four slightly larger chambers and that would explain the expanded brass that then does not fit in the smaller chamber.
Frankly, I don't know if it matters as one normally does not shove empty brass back into a gun. If they continue to eject fine, and do not affect accuracy, it seems like a non-issue. Maybe more of a problem for a reloader with the expanded brass.
Sending it in for peace of mind may be worth it to you anyhow. What's the worst that would happen?