If it's very dry then yes that could be the reason.
or it could be too wet.
if the compost is fine then check for vine weevil grubs in the compost. I have had them indoors before.

Thanks you. I have given it more water and its back to looking beautiful. Very strange as I water religiously but it mut be thirsty with this very warm weather (ha). Thanks once again.

glad it was nothing more sinister.

Thankyou