Follow these steps:

1) Measure the oil in your M8 engine following the procedure specified in your owner's manual. Your engine should be at or near full level. Take a picture of the oil level on the dipstick before starting step 2.
2) Ride the bike for about 75-100 miles with both highway speeds and higher rpm twisty roads, riding without significant stops or turning off the engine.
3) Use the same procedure in step 1 to measure the oil level at the end of step 2 without idling for any significant period at the end of the ride. Take a picture of the oil level on the dipstick at the end of the ride and compare to the first oil level picture.

A) If the dipstick oil level in step 1 equals or is close to the oil level in step 3, then your bike isn't sumping and is unlikely to sump in the future. Forget about sumping and enjoy the bike.
B) If the oil level in step 3 is down 2-4 rows of dots, then your engine may have a mild case of sumping as there is likely more oil in the crankcase than there should be. Its worth sharing your pictures and findings with your dealer.
c) If the step 3 dipstick level is very low (down to ADD OIL) compared to the oil level in step 1, your M8 engine has a serious sumping issue. The missing oil between step 1 and step 3 has collected in the bottom of your crankcase due to sumping. Share your findings and pictures with your dealer. It needs to be addressed before the engine fails as a result of sumping.

If you engine is sumping they will be responsible for ALL costs under your warranty. Don't let them screw you out of labor costs over 1 ounce of oil. Tell them you want the bike back as it is since there's no issue according to the MoCo. Follow the steps above and share the pics with the dealer and you won't pay a dime to have the oil pump installed if the bike is proven to be sumping..