Hello Clive and
to this mad world of Bsa and this wonderful forum ,which isn't mad , well only some posts , but where you will find an answer, the members are great friendly and knowledgeable . re your question I've never had an issue with cams and am not aware of any real problems, for instance ,my present bike was revamped about 14 yrs ago and I changed the cam but only because I upgraded to bigger valves and sportscam/followers but the original cam which had been in the engine sine I acquired it 25 yrs prev was still usable. I've keep it for that reason ,some scuffs and marks but serviceable .
I'm sure someone will be able to confirm if there ever was a production or batch problem with cams. I'd suggest that a look at the cam was required and comparing to another cam would show any wear ,incorrect engineering that there is . Not being an expert I'd wait for confirmation from more knowledgeable guys who will be around very shortly I'm sure .
How about an into in bikes pictures members to let us know a little about you your bikes etc enjoy Bob.