Matias keyboard and wake/sleep

After two days of effortless typing with the Matias (god, it really
*does* make a difference) I've noticed an interesting difference.

On the iG5 with 10.3.9, I normally sleep the machine by pressing the
power button on the back of the unit. Easy, reliable, instant (well, a
couple of seconds at most). I have checked System prefs->Energy
saver->Options->'Allow power button to sleep the computer'.

The wake options (if the modem detects a ring, or for admin access via
Ethernet) are unchecked.

With the Apple keyboard I would wake it by tapping the space bar. Worked
every time. With the Matias, it only works some of the time. If the Mac
has been asleep for a long period, like overnight, it doesn't respond to
the keyboard, but wakes fine if I press the power button.

This is no hardship, but I wonder why it's changed?

--
Peter
.