EGR Issue

[Powermoon]

Went in for a coolant flush and it looks like I may have an egr problem since I was low on coolant. I've noticed that the reservoir bottle has very slowly been getting lower and lower for some time and I've been in denial about the whole thing. The truck in my sig has 109500 miles on er, never overheated, and doesn't seem to be puking (If I remember correctly the tech said a leaky egr cooler?). After speaking to the tech he filled er back up with coolant, marked the reservoir bottle and said to keep an eye on it. My question is, when do I check the coolant level? Do I do this when the truck is cold (sitting over night or for several hours), or when it is warm (after driving for a while)? We are taking a trip to Central OR (approx 500 mile round trip) for Thanksgiving and the tech said I should be fine for the time being.

Also, I've been kicking around the idea of deleting the egr system (no emissions testing on my side of the mountains) but wonder what happens when I trade it in for something newer. Will I be penalized for this modification or will the dealership even check? Thanks to those who respond.