My radio has a digital display, so it's fairly accurate. Could the signal have drifted off frequency that far?
Chances are, you were tuned above the signal (and BFO'd to audible) whereas normally the rcvr LO is tuned below (and then BFO'd audible) ... the difference being about 4 kHz (high).
A 'consumer'/entry-level radio like the Grundig is a lot like the Degen in performance a couple of us have, and unless the IF filter is swapped out the IF (Intermediate Frequency) BW (Bandwidth) is about 6 kHz wide (maybe even a bit more) ...
A good, normal communications receiver IF BW is around 2.3 or 2.4 kHz wide. Modern ham rigs (like an Icom IC-756ProII ) are adjustable from 3 kHz to less than 1.6 kHz (and also shiftable and infinitely variable) and then the CW filters range from 400 or 500 Hz down to 250 Hz wide.