I recently found myself in a similar situation when I purchased my Daytona this past summer. The seller had traded his 600 GSXR to a friend for the Daytona. The friend had purchased it from the original owner about a year earlier and had put quite a few miles on her in that time. The seller assured me that both he and his friend were on top of all general maintenance on their bikes and they did appear to be well taken care of. Probably better than I currently do myself. However, I could never get comfortable about whether all of the 12K mile service had been completed or not, so I called the seller's local Triumph dealer, gave them the VIN # so they could check their service records. Not only was their no record of the 12K mile service being done, but also no record of the recalls for the fuel fittings and fuel clamps being done. Always good to know before the cash changes hands exactly what you're getting. Having said that, after a 20 minute test ride, I'd have paid the seller's original asking price if he'd pressed hard enough!
Anyway, your local dealer should be able to tell you what recall work has been done (or not done), and if you know where the previous owner had the bike serviced, that dealer should be able to tell you if any of the 12K mile service was done. BTW, the service tech where I had my 12K mile service done said it looked like the engine had never been opened, and that the inside looked like new. All the valves were still within specs so no adjustments were needed. They also did the recall work, which since it involved removing a lot of the same parts that needed to be removed for the 12K mile service, I asked them to do the recall work first, and cut me a break on the shop time for the other service work. In addition to the normal 12K mile service (valve check, throttle body synch, new air and fuel filters, replaced fork oil, flushed radiator etc), I had them mount a new front tire (supplied by me), mount new front and rear brake pads (supplied by me), clean the caliper pistons and replace the seals, load a new TOR tune and install a 17 tooth front sprocket. I had recently done the oil change so they didn't do that. All this set me back just under $400. I do wish in hindsight that I'd asked them to record the valve clearances just to have as a reference for next time, but no big deal I guess. Whew, it must be Friday! Good Luck.