Yes, that's what the story was. Not sure the origin of it. The cover ended up being completely black too besides the 0.
Cheers. I found this online just now:
http://www.recalledcomics.com/ASM638-2ndPrintVariant.php
An extract from it says:
"Anecdotally it was suggested that the second printing was abandoned/recalled as a bad idea: The "O" on the cover was meant to be the first of three with the "M", "I" and "T" to follow possibly as second prints to each of the four issues in the storyline. (Note: O.M.I.T. spells out the initials of the storyline and is also a reference to how Parker's and Watson's wedding was OMITted from the continuity, according to Quesada).
Another explanation (from multiple sources but likely originating from Chuck Rozanski of Mile High Comics) was that there was a truck wreck where most of the second prints were destroyed with only around 800 surviving, which were liquidated later by Diamond with one dealer buying the lot (and Chuck apparently bought some from him). Note that copies (likely a small number) also seem to have made it across to the pond to the UK but Marvel did not print more copies of the second print for the North American market."
My old copy wasn't completely black - you could still see the cover image behind the 'O'. I always thought it was an odd cover.