It all comes down to the question of how you stored it I suspect.
Stored right, the weed should pretty much continue curing. Thus get better with age. Tobacco gets better with age, like wine, and stuff like that, but only if its stored right. Like a fine wine, if its not stored properly for long term it can spoil. Not saying your weed has spoiled, but if you notice a degree of degredation over time etc...
For longer term storage, I'd use an airtight or vacuum storage system for the bulk, and seperate out amounts to last a month or so, that way you're keeping the main stuff in a dark, low air, low humidity environment. Oxygen is what spoils things, so might be worth having a look online for some better storage methods - you get containers for the longer term storage of food etc, they'd be a good bet for keeping your stash fresher for longer etc. If you're also operating one main bag and dipping into it regularly, that disturbs the buds and in theory you could be lowering potency by ruffling the buds that you haven't got down to smoking yet.
Its not just about the THC, its about the CBD and hundreds of other little chemicals. CBD is believed to be responsible for the physical stone. THC gets you high, but its not the be all and end all, as someone who likes the physical I often have more interest in the CBD values, its also one of the reasons those of us who like it heavy wait for the trichomes to turn amber before we harvest.
If you get drug tested by the police at the roadside etc, and you're sober and haven't smoked that day or the last few days, just act surprised and say it must be passive smoking from a mate who does smoke. If I find myself in that situation, I'd blame my brother ... he smokes "funny tobacco" and I really don't approve of it ... occifer, lmao