Hi Michael,
If this was today (August 1st) then I’d check again on your full account tomorrow. Fortunately you haven’t committed an offence because you held a valid travelcard and an extension ticket. It’s possible that the gate was faulty, or that it hasn’t uploaded it’s touches straight away.
If the touch in doesn’t appear tomorrow then it’s up to you whether you report this to the helpline. You’ll neither have been overcharged nor undercharged, so it’ll just be to report a curiosity.