About a month ago I flushed my cooling system and filled it back up because it hadnt had a flush in 2+ years. Unfortunately when I was driving it home from my friends garage it started to overheat, I didnt notice until the temp gauge was up to 2/3 on the gauge. I immediately pulled over and shut it off, turned out the Thermostat was stuck closed. I replaced the Thermostat with a new one but now every time I drive my 7 the temp goes up to 1/2 on the gauge rather than the 1/4 it was before. My question is: does that mean my coolant seals are blown? or should I do the test to find out (the test under the FAQ for overheating & coolant seals).

I have checked everything else I know to see if it was responsible for the overheating:
-Checked all coolant hoses for leaks, etc.
-Checked radiator for blocking.
-Pressure test on radiator and filler caps.
-Checked fan clutch.
-Checked water pump drivebelt.
-Ignition timing checked (not personaly)

None of these tests came up with anything. Im checking with you guys to make sure I didnt overlook anything. If anyone has any suggestions on what else could be causing the overheating please say so. I also have the Haynes repair manual but I'm a newbie to this kinda stuff so im trying to learn all that I can. Thnx.