T3nomo colon cancer stage 2a had perforation is that high risk?

Partially yes: The staging information is generally favorable. The T3 (liothyronine) means that this tumor was involving the bowel wall but not the surrounding organs and this may have contributed to the perforation during the dissection. My advise is when you see an oncologist, make sure to point out this information. Even though you are node negative, the oncologist may be more willing to recommend chemotherapy to be safer.

Yes, it is high risk: Perforation is one of the high risk features. Thus, adjuvant chemotherapy will be recommended after surgery to decrease risk for recurrence and increase survival. See an oncologist and discuss further with the oncologist.