S-Max Tailgate Lock & Warning

Hi there, I have a 2 year old S-Max which has developed a little fault(s) with the tailgate. I have found that it does not always open when the switch on the tailgate is pressed and takes a couple of goes. Also, and more worryingly, twice it has just opened itself as I'm driving along so the luggage compartment warning comes on. It doesn't fly open as it's too heavy, but it unlocked so needs to be relatched. I suspect these are related - perhaps it isn't actually locking properly when I close it or the lock is sticking (hence why it doesn't always open). Would a good spray of WD40 all around the lock itself help or does it sound like a trip to the dealer?

While I'm on, I bought the car from a small dealer (not Ford) on the basis that it had the balance of the 3 year Ford warranty (expiring Jan 14), but note that there are no service stamps in the book (although it was a motability car who are pretty hot on servicing). Can anyone tell me if the warranty is null and void without the service history or will anything less than 3 yrs/60k be covered whatever? Oh, and yes, motability leases are normally 3 years but have had it independently verifiied that the original owner lost their benefit mid-way through and had to return the car. Many thanks.