I'd take it to the dealer and have them look it over. Last week I accidently road over a lane medium as I was turning left, a moment of fatigue and innatention caused me to cut the curb short and I had to clear it all the way due to approaching traffic.
I looked underneath and I though all that happened was I broke off the lower plastic molding that holds the front bumper to the oil pan strike plate and a few scratches on the exhaust.
Instead I did well over $5,000 in damage. Several metal plates were curled, the oil pan strike plate was dented in at the center jack point, which put a dent into the main lower sub-frame aluminum machined frame that holds all the front lower suspension arms to, luckaly no damage to the actual oil pan of the engine. That part cost well over $1,000 plus 10+hrs of labor and an alignment, plus alot more crap.
So just a scratch isn't the issue. Depending on how you hit and how much impact, especially at higher than 20mph you were going, could have bent stuff you don't know about. Just go have it checked out. I didn't think my damage was that much because I ran over the medium at about 10 to 15 mph and it was a mess. Good luck.