Just seen your reply
Ab Editor!
That's what I thought too it was a bit odd. It seems to have settled so I'll leave it be for now but may try your suggestion.
I wasn't sat under air con - the shop is on the shady side of the street but I had people comment on how warm it was - heater wasn't on.
I remember one my mum was given were you walk your fingers up the wall until your arm is vertical...that helped too but I couldn't really sit with my arm in the air all the time.
Thank you for the sugggestion I will give it a bash :)