is this an epidemic?

what is up with all the overheating problems out there? heres my story. car ran great, the autometer was never past 180*. car went in the shop and now she runs at 210* or so all the time. when i sit at idle, she goes down to 190 or so. then on the street she goes right back up. never overheating, but i think that running at 210 only gives you 40 degrees till the danger zone. and thats not a lot of wiggle room. she has new t/stat. 180* (was thinking of putting in a 160*) before she went in the shop i put in new w/pump...rad...and hoses. cant quite figure it out. any ideas? thanks ed

i understand the therm closing and opening. im saying that after she came home from the shop, she ran 40* hotter than when she went in, i pulled the therm and put in another new pstat 180* but she is still driving around w/ the temp at 75 mph at about 210* or so. i dont like it that high. and im just stumped at why its doing this all of a sudden, running so much different. 30 - 40* is very diff all other things being equal(except outside free air temp)(ie spring vs summer temps) it bothers me when i cant figure something this simple out is all. other than that she runs great. im putting a blowzilla on her after i get to my next duty station in kansas about march or so.