I’d be surprised if it was NOS, my guess would be like you’ve said has had a service and is still under Panerai’s 2 year warranty. If you ask for the serial number you’ll be able to date it from this. In my experience some of the staff really haven’t got a clue, I recently visited and bought something from their Mayfair Boutique, short story…. She swore blind that the watch I was buying was SS, it was in fact titanium, it was so blatantly obvious, but she still insisted it was SS…… didn’t bother me as it was priced at SS money :-)
Percentage of their sales staff are just ‘order takers’ no real knowledge watches sadly, I do buy from them occasionally but always do my own research first- I’d suggest trying Will from wiseman watches, true enthusiast and knows his stuff, if he hasn’t got something would more than likely be able to source you something at a competitive price.
Hopefully you’ll find something Panerai, such an addictive brand and you’ll have fun buying numerous straps…..