I just purchased a new Kenmore oven and the manual calls for a minimum of 8 Gauge solid copper on a 40 Amp circuit. I went to Home Depot and purchased 60 ft. of 8-3 with ground. When I got home I noticed that it is NOT solid copper but stranded copper. Will this matter? the manual specifically calls for solid. should I worry about it or is it ok since it will be on a 40 Amp breaker?

Just bought the place and don't want to burn it down! (wife would be angry) Thanks.