If the light was off, the delare turned it off, ought to ask what they saw and or fixed. If the cap is a little tight, it isn't the problem. I would call them in the morning and tell them about it, you want it scanned and repaired cause it could be a big deal.
Best wish for the rest of the new truck thing, and yes pictures are required to do any additional posts.
Mike

 

Congrats on ur new Disco, Enjoy it. Landrover's are truly the ultimate 4x4