Hi,
A few months ago, I bought a CX-7 used and it had problems reading some discs - upon loading, the display would just continue to go around for about twice the normal time, I would hear a slight 'scraping' noise from inside the player, and then the two dashes would show (as if empty) and the disc drawer would open. Many times, it would take quite a bit of coaxing to get it to read the disc. Sometimes it never would. This mostly happened on brand new Cd's.
I took it to the Ayre factory to have it upgraded to a "e" and they replaced the laser lens assembly to address the problem (Michael and the folks at Ayre are great). It is a lot better now, but it is still occasionally picky about what it will read (but usually acquiesces within 3 tries). Sometimes (too much) it will hit a place on a CD where it pops loudly, often once, often many times, and then the drawer will open on its own (sounds like your issue). Unloading and reloading the disc works sometimes, other times the disc must be cleaned before it will play (even though I see not evidence of dust, oils, or damage on the disc's surface).
I do not know if this is unusual for this model. It sounds so darn good that I have just tried to get over it.
Yours being just 6 months old, I would definitely call Michael at Ayre. My guess is that it will only get worse over time without a repair.
Please let me know what they do and whether it fixes it (crossram2x4@aol.com).