GAS ESCAPE FROM GAS FIRE?

We had a gas fire installed approx 2/3 yrs ago and were very pleased with product , the pilot light requires a match to ignite , my problem is there appears to be gas escaping from behind the the main control(rotary switch) which I can ignite and will contue to burn whilst the fire is turned on but stops when fire is turned off (suggesting it is a feed to the pilot light), can this be repaired? as there is no permanant leak its as if something has slackened off.
any suggestions welcome