If the oil LEVEL was ok, and the oil looked a tad milky, could just be normal condensation or incidental water ingestion that happens and comes from running and playing hard with them. Sometimes the way we run is a little nuts (Nordie), like driving directly under anothers roost! Waters bound to get in there some. I wouldn't sweat it so much, usually evaporates off, or in a severe case, such as the latter event, an oil change might be required, but not an indication of a real problem with the engine.

If the oil LEVEL is WAY up, like a quart or even more and REAL milky, yeah, you got an issue, and could be a serious one. (Recently had one of those!).

Running the engine 10 minutes...Hopefully with the driveline disconnected and on a hose, or on the trailer in the water, would not be sufficient to warm everything up or cycle the engine unless the rpms were run pretty hard. Also look at the water coming out of the engine (On the ground) for the "rainbow" that is oil or fuel.

Hope this helps......some.......milkshaked more than my share already!

Ray