Does anyone have an explanation for this strange thing?

Sometimes when I do a New(P); P^ := something

when I step through this area with TDX, the de{*word*81} traps to some
strange routine when P^ is accessed.   It's not an explicit call,
so it's probably some trap on access thing.  The call returns okay and
the program continues as if nothing had happened.

Doesnt the run-time allocate memory on the New() call?  Or is there
some delayed allocation that is delayed?   I don't like strange things
like this happening behind by back!