I would use 5W-20 in the future. If you live in a hot climate year round 10W-30 would be fine (Texas, FL, AZ, southern CA). If you live where winters get cold 5W-20 is best year round.
I suspect no damage done, you might have lost one or two mpg due to thicker oil. Reasons for 5W-20 is better fuel economy due to less internal friction in the motor. In the winter it is also much easier on the starting motor when 0W or 5W-20 oils stay thin at sub freezing temps.