Broad stood his ground after edging a ball in the second innings from Ashton Agar to slip, via the gloves of Brad Haddin, when on 37 - he went on to make an important 65 - after umpire Aleem Dar had given him not out.
The 27-year-old received strong criticism in some quarters for his decision, but insists it was not clear cut at the time.
"It was an odd one. There was no particular noise because of the noise of Haddin's gloves," said Broad, who is an Test Cricket Ambassador.
"It's a bit silly when people say it was nicked to slip because actually it was edged to the keeper's gloves and flew off the gloves to slip.
"I went down to the other end and Ian Bell was like 'what happened there, I didn't hear anything?' Agar came up to me and asked if I'd nicked it because he wasn't sure.
"So it wasn't as clear cut as everyone had thought, although I knew I'd hit it.
"Walking's an interesting one. You have a split second and sometimes when you edge it you walk out of pure frustration. You kick yourself and walk away.
"For players on the field not to have known if I nicked it proves there was confusion there."