Cadillac Escalade cooling question

I have a 2011 Cadillac Escalade ESV with 151K miles on it. I noticed earlier this summer that it seemed to run the fans more than I thought they should. Well a week ago this got extreme. I plugged it in today and ran it on live data for the ECT (engine coolant temperature) and saw some things I think are weird.

1- it was between 60 and 66 degrees today when I was doing this so not hot at all. 

2- I drove it ~25 miles to work and back, the trip is uphill half way and then back down the hill. Going down the hill there is almost no engine load, for most of it you could put it in neutral and coast

3- going up the hill I was ~230-234 degrees and the high speed fan kicked on

4- going down the hill the lowest temp was 221.

5- On the way home I stopped at the car wash. while sitting in the car wash the high speed fans turned on almost immediately and the temp continued to rise until it got to 243. It never came down until I started driving again and it was still at 237

I am pretty sure this isnt right and the high speed fans should drive the ECT down to less than 220. Does anyone have any thoughts on the root cause and what I should be checking?

Pic of the data trace

Just had this happen with my 2015 silverado.  It was low on coolant.  I don't see any leaks or anything, I'm guessing it just list a little over the last 10 years...

Anyway, check your coolant bottle (it is pressurized on my truck so I had to wait til everything cooled off).

Good luck!

Good call for step 1, I will do that. I haven't even popped the hood. Just checked the temps and asked questions before I even looked at it. 

It was a little low, it took almost a half

gallon. I didn't think that was a lot but it changed everything. It was about 10 degrees warmer ambient and I just let it run in the driveway, probably 20 minutes. The low speed fan would cycle on and off. Temp stayed just over 200. 

Hopefully that was it!

Well it is never that easy, I knew the coolant had to be going somewhere. After letting it run in the driveway and sit, I saw a small puddle under it, it's coolant. I think it is leaking where the plastic tank side attaches to the aluminum. Not positive but I don't see any wetness at all under the hose. See attached, maybe I am wrong?