Spray that again?

Today noticed a thin film of spray on the windscreen. Not unusual for North West England I hear you say! I’d agree but it wasn’t raining & the spray was driver side only of the screen. It can only be coming out of the engine via the bonnet vent (nostril?). The ‘taste test’ was inconclusive but I don’t think it’s fuel, so probably coolant. Couldn’t see anything obvious around the radiator, lose jubilee clips etc so may be (another) garage job. In the meantime loving the autumnal sunshine in September. One of my favourite times of year to be out in the Mantis with hood down feeling that slightly crisp edge to the weather which says summer is over. Wonderful.