Seems like good news to me as well, but we need to read a little more into this. I see 3 things to consider if anyone want to make short term bets based on this:
1) If Panasonic is saying that cell production could soon increase, it means it has not increased yet. From cells to packs, including the aging process, I imagine that is a few weeks, then from packs to cars, that's another few weeks. If I were to trust this on face value, then it may take several more weeks for this to propagate to M3 delivery.
2) Tesla may not have told Panasonic everything about the M3 bottleneck, so there is risk of other unknowns still delaying M3 ramp. If Elon comes out tomorrow pumping his chest and says design studio opens by such and such date, I would feel more confident.
3) Panasonic is saying this to appease their investors of a slower than expected quarter. From their perspective, if they can raise the production in a few weeks or several weeks, as long as things look good by the next quarter, they will be fine, but this may not translate to an immediate uptick in M3 delivery.
So in summary I think while it's good news for sure, the details on timing seems very "soft", and not much to go on if we're looking for short term improvement in M3 delivery.
Edit: I think it does significantly increase the likelihood that mass M3 delivery will be happening by Dec or Jan timeframe.