Hey HomeMaker,
Congrats on the new house! The black dust around the can lights could be from a lot of different things. Did you have a home inspection done on the house prior to purchasing? Is the dust inside the can on the trim, or on the ceiling around the can? The dust could simply be from the grease and smoke that cooking in the kitchen creates, but it could also be from the light getting too hot. Most recessed lighting fixtures arent made to contact insulation. They can over heat if insulation is covering them in the ceiling. Electrical is very serious and dangerous I would call an inspector if the light seems to be getting too hot. Be safe.