Colchester substitute Anthony Wordsworth was booked after 40 minutes for allegedly interferring with a corner being taken, even though he was not on the pitch.
Trollope said: "It was the first time I have seen that happen. I wanted the corner retaken because we were looking threatening from set pieces.
"I'm happy with a clean sheet against a side that have been going very well since Paul Lambert took charge. We had the better of what few chance there were, but the quality of our crosses let us down on occasions
"We have another home game against Cheltenham on Tuesday night and if we can win that one we will be moving towards the mid table position that we need."