[Someone]

As zodiac said: yes.

I think the printer knew he needed large parentheses, but didn't have them available (or he had used all of them elsewhere in this edition of this journal), so he went for something similar that he had instead.

Knuth's rationale for writing TeX is full of this kind of observations on mathematical typesetting: letters that become larger in some places, italics that disappear, tiny font changes, etc.