Incompatible coolant?

[GreenDiesel]

When I bought my car it had the nasty green coolant in it. I recently flushed the system and refilled with Zerex G05. The basic process I used is as follows:

1. Drain old coolant from radiator petcock
2. Drain from block
3. Remove thermostat and install housing without thermostat
4. Refill with system with water; bring to operating temp with heater on full
5. Let cool; drain system
6. Refill with Prestone flush; bring to operating temp with heater on full
7. Let cool; drain system
8. Refill with water; bring to operating temp with heater on full
9. Let cool; drain system
10. Refill with water; bring to operating temp with heater on full
11. Let cool; drain system
12. Install thermostat
13. Refill with Zerex

After a few days I noticed that the nice new amber coolant I had just put in now has a slight green tint. Before I replaced the thermostat, expansion tank cap, refilled the fan clutch and flushed the coolant with temperatures around 100F my car had been getting up to 100C (mostly in stop and go traffic). Afterwards it stays pretty consistent around 85-90 in traffic but now going 80mph on the highway or up hills at 85F the temp will climb to 95-100C (no AC). Could the slight bit of green coolant apparent in the system be reacting with the new coolant and causing this problem?

I'm thinking about draining and heavily backflushing this weekend but I wanted to get some insight if there is something else I should look for?