I thought it was just me.
Same issue here - it usually takes three presses of the power button to get the expected behavior, no matter what the expected behavior is. Such as when sleeping to get it to wake, or when awake to get the power/reboot/sleep menu on a long hold. It seems like it's too sensitive. It actually will wake on the first press, but then goes right back to sleep, like maybe it's detecting two presses (a wake, then a sleep). Pretty annoying.
It seems to have started with beta5, but I wouldn't swear to that. I was running MoDaCo superboot, then CMb4, then b5. It definitely was not an issue with MoDaCo.