When you age a wine or mead you need to either make certain that there is no headroom in the carboy if you are bulk aging or that when you bottle it , the wine (or mead) is crystal clear and has completely stopped fermenting.
Headroom will fill with air and oxygen in the air will oxidize the wine as it ages over months.
If it's not as clear as glass you may find that sediment will drop out of solution and that detracts from the quality. And if it has not absolutely finished fermenting then when you cork or cap the bottles CO2 will continue (even very slowly) to build up exerting pressure on the glass and on the cap and eventually one or the other will give up and you will have either bottle bombs (exploding glass is very dangerous) or a gusher with the loss of the contents of the bottle - and a messy floor or wall or ceiling to clean up