Moscafj's answer is technically true, but I don't think that you will have any problems with your containers.
Exposing your spices to drafts, convection and change in humidity is a bad idea, it will make them lose their aroma quicker. This is why they say "airtight container" - so you don't keep them in an open jar.
But if you have pinhole-sized holes in your spice containers, the rules of physics say that there will be very little to no air exchanged through them. They are just too small to allow for any noticeable convection, all you get is a tiny bit of diffusion. In other words, a screwed-on cap is OK, you don't need to put an o-ring beneath it :)
If you keep the container perfectly airtight, the volatiles which escape the herbs and spices will stay captured in the air around the spice. This will certainly smell better when you open the container. Also, they will lose less volatiles according to Nernst's law, because they are not surrounded by pure air, but by air in which their aromas are already dissolved. But, as I said, the air loss through not-hermetically-tight containers is so small, the difference is so small that you won't notice it. Maybe you'll need half a pinch more dried oregano to achieve the same taste intensity in a batch of sauce after some months of storage in closed vs. hermetically closed container. And the more frequently you use the spice, the less pronounced the effect, because you lose the satiated air whenever you open the container.
As far as safety is concerned: spices are shelf-stable, it doesn't matter if the container is closed or open, they are always safe to be held at room temperature.
So, as a practical matter: standard spice "shakers" are good enough, no need to caulk them shut or buy new ones.