Question on MZ-S quirk

[Joe Wilensky]

I grabbed a like new MZ-S from KEH last month (it truly was like new, 
and only four rolls had gone through it based on the data imprinting 
count -- I don't think it was reset, either, because it looked like it 
had never been used at all). I had borrowed an MZ-S from a list member 
briefly a little over a year ago, and had been thinking about the MZ-S 
ever since ... anyway, the question is whether this is a quirk -- I 
changed the Pentax Function 6 to make AF and AE both lock with a press 
of the AF button on the back. I didn't realize it at the time, but this 
completely disables the AE-L button on the back so that it has 
essentially no function at all. (It will still "wake up" the camera to 
give a meter reading, and it still will select Pentax Functions in the 
PF mode, but it will no longer lock exposure.) This is true for the 
AE-L button on the grip, too. I couldn't remember if I had tried the 
AE-L button before this, and I was truly bewildered until I thought to 
switch the PF back so that only AF is performed by the AF button on the 
back. Lo and behold, the AE-L button works fine again. The manual, of 
course, makes no mention of this. Is it a quirk anyone else has 
noticed?

Joe