Water blow out for winterizing

[4Daughters]

So we finished the 2016 camping season this past weekend and we always drain the water out of the trailer. I ride down the road with my low point drains open until I return the trailer back to storage. Today when I went to winterize, there was very little water coming out using air. The most water came from the outside shower. I pulled the anode rod as well and no water in the hot water tank. Does this sound reasonable? We are expecting below freezing temps but rising above freezing during the day so I only put antifreeze down all my drains.

On another note, I noticed my long slide topper was holding a lot of water Sunday morning when we broke her down to leave. Is this normal?

Again thanks for all of the helpful replys.

[5picker]

Both items are normal.
Leaving the low point drains open while traveling will remove a lot more water from the plumbing system than when the unit is static. The movement and sloshing of the water contained in the plumbing will work its way out when moving.

My slide topper will sometimes hold water too. Especially the longest one.
I don't consider that a problem. I'd rather it be on the topper than the slide roof.
Some folks will level slightly low in front or back to help alleviate this condition.