Yup, an account of this incident was also published in "Starman" by Jamie Doran and Piers Bizony, published in 1998 -- a biography of Yuri Gagarin. Only they pointed the finger at a low-flying Su-11, based on reports that surfaced in public in 1995 ...

http://www.amazon.co.uk/Starman-Truth-Behind-Legend-Gagarin/...