posts like yours are the reason why i chose not to publicly post on PPRuNe,
But you did post publicly on Pprune - to tell the whole forum that you've sent a message to the OP. If you wanted to keep things private, just send the PM without the announcement. The OP will see it as soon as he or she logs on again. He or she may even have email notification if its arrival.
If it was information which others may find useful, why not share it?
Cheers
Whirls