The neutralizer used to perform a titratable acidity test is a liquid sodium hydroxide reagent. I’d recommend you always purchase and use a dated reagent—the hydroxide weakens in time and can lead to incorrectly high TA results. A best practice is generally to replace your sodium hydroxide at the beginning of each harvest season. If your reagent is dated and stored cool and sealed, you may be able to successfully use it for two seasons.
If you are questioning your test results and freshness of your sodium hydroxide, that’s good, you should maintain some reasonable skepticism about the viability of the reagent. On this point, I’d recommend to always taste the wine in question as a double check on your results—a high acidity result should correspond with a sharp and hard to drink wine, don’t you think? If the tasting and test results don’t seem to correspond, perhaps its time for fresh hydroxide.