Being dried for a few months is not really sufficient. The norm is 12 months for each 1" thickness. I realise they are only thin boards but the natural oils as opposed to moisture, take a long time to dry out. This doesn't affect movement etc but does affect the tonal properties. When storing/drying 'green wood' you should always 'sticker'. Best to strap it down over the stickers to keep it flat, and store in a draughty environment where the moisture will be carried away. Outside is best (kept dry, under tarp, off the floor etc) with a few months extra conditioning in your house/workshop.