I have an online roaster I use. As I'm still very much a beginner, I only buy the same beans - a dark Indonesian roast, 1Kg at a time. I then freeze 750g in three bags and go with 250g in the grinder, which lasts me about a week and pull the 250g out of the freezer one by one.

The roaster prints a roast date on the coffee and this is always on the day they dispatch it. Even if I get the email from their system that they've dispatched it an order I placed at 6AM 5 hours later at 11AM. I always thought this a bit suspicious, but I like the taste of the coffee and can't yet be bothered learning to dial a completely different bean so I persevere.

But of the 4kg batches I bought, 3 have shown a definite need for me to adjust the grinder finer and finer each day as I go through my 250g batch in order to keep the shot time constant. Even when I pull the 250g batch out of the freezer this process still takes place. This I would expect and to me seems consistent with freshly roasted coffee still degassing a bit - even for a dark roast.

One 1kg batch however, still had a roast date on the day of dispatch but did not require any grinder adjustment, and it also required grinding way finer than the other batches to achieve the same shot timing (dose is constant throughout).

Should I be suspicious of the roast date which is claimed on my packages, or are there other possible explanations for this?

Usually as it gets older and staler I have to grind finer, so that kinda makes sense for those 3 bags. Perhaps the last bag de=gassed and staled quicker? Or how new is your grinder? usually with burrs seasoning you get finer and finer.

I am not sure based on your post weather you put the bag back in freezer each day after taking out the beans you need. This is is important, i freeze in 16oz mason jars no vacuum and take out the beans I need for the day and put jar back in freezer. Grind settings don't change and I have a big flat burr.