I'm guessing it's higher mileage than 60K and so would then be out of warranty.
Although I'd still be inclined to take it to a dealer, just don't mention the correct mileage as they don't always check!
Just had a look in my handbook, but it's not much use.. Just says the alarm is activated when:
any door is opened
the bonnet is opened
the ignition circuit is turned on without the key being used
Someone else might know more and post up.