Hi all parked up for a while earlier with my engine running and my temperature gauge started straying from its usual 90 degree point, i didnt even let it get to the next marker before switching her off and popping the bonnet, now recently i changed a few small coolant hoses to silicon ones, it seems that one of them (pictured below) is leaking, could this cause my problem,? or am i looking at the temp sensor, thermostat, route?
The upper of the two red hoses on N/S of inlet manifold

The upper of the two red hoses on N/S of inlet manifold