You MUST patch it! I had exactly the same situation 2 weeks ago when I moved to a new house, the previous owner had removed his dish and left 5 holes on the shingles. Then Bell guy came to install Expressvu for me and drilled new holes without reusing the existing ones! it was raining that weekend and we found out right away on the inside wall of the garage, water came down along the wall..
To fix it, go to Home Depot or C-Tire and get a silicon for roofing. You'll need the silicon gun as well. Do it quickly as rain is forecasted in a day or two.
Good luck!