The Geordie Shore star was notably subdued and shocked to see his ex-girlfriend Lillie arrive on the beach in Tuesday night's episode (6 September).
Speaking to the Shack of Secrets afterwards, Gaz said: "I just had a feeling it would be Lillie. I forgot what she looked like, I forgot how she spoke, the sound of her voice, her mannerisms. I forgot everything that she was like and that was the weirdest thing."
Gaz was very quiet on the beach, barely looking at Lillie when she spoke. It was the first time they'd met since their break-up. They split in November 2015 after more than a year together.
The pair didn't really interact all episode, as Lillie was sent on a date with Stephen Bear as soon as she arrived at the beach, then spent time with the girls back at the villa.
But Gaz has told readers of his Daily Star column that changes in upcoming episodes. "F**k me, that was emotional. It was hard seeing Lillie come out the beach but this definitely isn't the end of the story. There's lots more to come on the show," he promised.
Gaz also confirmed what he said on Twitter this week: he and Lillie are JUST FRIENDS. Rumours of something more surfaced when they were snapped together at the same club.
"Like I said on Twitter this week, a couple of grainy shots taken on a phone in a club show nothing other than us now being mates. Tune in to MTV at 10pm next Tuesday to see it all going off on Ex On The Beach."
Lillie, meanwhile, has said: "This is the first time I've seen Gary since the day we broke up at the airport. There is so much we need to talk about. My mission with Gary is making him realise how badly he's actually treated me. I want him to understand what I've been through, apologise and just move on. Close that chapter."
Watch Gaz and Lillie chat their first meeting below:
Ex On The Beach 504 | Shack Of Secrets: Lillie's heartbeak and Bear thinks Gaz is a muppet
Watch More: www.mtv.co.uk/ex-on-the-beach