I highly doubt any damage was done. If there was only a small stain in your driveway and the oil light (pressure light, not change oil now light (wrench)) never came on and the mechanic isn’t lying about their being plenty of oil in the motor then no damage should have been done at all other than the missing dipstick and the mess under the hood.
As a follow up I thought everyone one would like to know that in addition to taking care of the dipstick the dealer detailed the entire engine and car and thoroughly washed the insulation pad on the hood. The engine compartment is super clean now so as long as there is no damage done to the motor I am probably ahead aside from the lost time. Thanks everyone for your advice. Would have never thought to get the engine detailed without your help.
It is always nice when a business owns up to a mistake and makes an effort to right the situation.
Now, open the hood and check your fluids every few weeks from here on out. 