2007 Silverado 4.8L oil leak on starter

I'm a newbie here and wanted to get some help on an oil leak I found. I have a 2007 (new bodystyle) with a 4.8L, truck has 90,000 miles on it and I've noticed an oil leak on the starter bolts. Just went on vacation and saw that with it sitting for 5 days it had created a spot on the concrete. Recently I brought the truck in to have the transmission flushed and I informed dealership of the oil leak on the starter bolts. Before it was brought in I checked to make sure it was still there. Brought it in to the dealership I bought it from and they said they couldn't find an oil leak and put dye in it. Remarkably when I got the truck back it was cleaned up and no oil was visible on the starter bolts. Well its been two weeks and I noticed fresh oil on the starter bolts. I'm going to take pictures of the fresh oil this time hoping they tell me it isn't an oil leak. I've heard this can be the crank position sensor any truth to that. My guess is the dealership seeing it only has 10,000 is trying to kick the can down the road.