I had a colon resection because of several bouts of diverticulitis.. 5 yrs later i have another infection ... thought surgery was a cure?

Diverticulitis: You might have had diverticulosis in other parts of your colon.

Not necessary: Disease may return , you have resection of badly diseased segment only , but have disease on most of the left colon ( even entire colon in rare cases ) , it is possible that disease may return in some cases , resecting the entire colon is a drastic step , not done