2012 Mazda 3 Electrical Smell

I have been driving some time and I just notice the Electrical type of smell coming from inside, checked tires checked engine I don't see any burning or smoke. My car gauges are operating normal as well. The smell has gone but comes back time to time. Car was serviced June 15 2015 no issues just that my tires are starting to Cup and need to be replaced and I need to get a alignment as well.