The TV presenter's first thought when she saw Kevin was that he had done his knee in - he has had several operations on it - or he was having a laugh.
"Kevin would be a bit of a devil as well, that he would pretend, so you wouldn't know with him," said Anna.
"He has had a few operations down through the years as he plays a lot of hurling.
"When I turned around first, my instinct was to ask was his knee giving him trouble or something, and then I was like, 'Oh, wait - that's not what's happening here'. "I was really blind-sided."
The couple, who have been together for three years, kept their engagement under wraps for a few weeks, savouring the moment together before revealing their big news on social media at the weekend.
Anna told the Herald there were key details in the proposal that showed her Kevin knew her well, as he used a promise ring to pop the question as well as picking a relaxed setting rather than a busy restaurant.
"We're going to choose the ring together," the Dancing With The Stars finalist said.
"A ring is very personal to someone and has to suit their style and your finger.
"He knew me well enough to know not to go flying solo on that one.
"I think it has to be something that even suits your personality - different rings suit different people.
"I have sports hands, so I don't have delicate fingers and need something that won't get lost on my finger."
As for the style she is on the lookout for, Anna said she had never thought about it.
"I don't have a preference, but right now, in my head I have white gold," she said.
"I'm going to go in with an open mind because if you go in looking specifically, you kind of narrow your options.
"I'm not an expert in engagement rings, I've never looked at them. I know some women would be like 'This is the one I want!' but I've never been like that."
For now, Anna is focusing entirely on studying for exams, saying she won't be celebrating properly until they're out of the way.