Not a question I've often seen asked but good question. You are correct in your thinking. There is no problem storing puerh in airtight containers. For many collectors once a Puerh tea has undergone sufficient ageing and reached its peak, it is carefully wrapped in plastic. This discourages further ageing and will lock in the aroma and flavor of the tea.
FYI I am working on articles on wet and dry storage that I will upload soon. If you are interested it will be made available at http://www.puerhcha.com/Pu-erh%20Tea%20 ... ticles.htm