Assignments in PL/pgSQL

Hi all,

although this is not really SQL, but PL/pgSQL, I hope this is the right
place to ask.

I have written a complex triggers. It works very well. Just now I have
realized that I have used the = operater for variable assignments, instead
of the := operater. To my suprise, there was no error or warning, and the
store procedure works very well!

e.g.
NEW.someval = rec.someother;
works as well as
NEW.someval := rec.someother;

Can you confirm that both are valid? Can someone explain this?
And is it safe to use the former syntax?

Best Regards,
Michael Paesold