GEELONG defender Tom Stewart has taken to social media to clear up a "misunderstanding" that he set out to play a practical joke on journalists.

The 24-year-old trained with the Cats on Monday afternoon after claiming earlier in the day he had been sent home from the club due to a bout of gastro.

Stewart explained the situation in an Instagram post on Monday night.

"(I'm) very excited about the thought of a prelim this week," Stewart posted.

"Now about this food poisoning/gastro misunderstanding today. I wasn't feeling great yesterday and accidentally mixed up my words when speaking to the media today.

"(It was) a complete accident on my part and take full responsibility for the mishap.

"Just wanted to clear the air and make sure everyone is informed. Clearly need some more media training."

In a doorstop interview on Monday morning, Stewart told reporters he was leaving Simonds Stadium for the day to ensure the illness did not spread.

"Gastro, food poisoning ... one or the other, so hope I'll be right," the first-year player said.

However, Stewart returned to the club for training later in the day and was not isolated from the players or staff leading to the conclusion he may have been making a practical joke.

Cats coach Chris Scott also clarified the matter to allay any concerns, saying it was "a misunderstanding but he's fine".

"He had a bit of gastro yesterday," Scott told Fox Footy on Monday night.

"The doctors at this time of year, in particular, get paranoid when anyone's got even a sniffle and they get removed from the playing group pretty quickly.

"So that happened yesterday … and in a pretty honest and raw moment he's walking out of the club, he got doorstopped and he's like, 'I've been a bit crook and been quarantined', which was absolutely true.

"But he was not so bad that he couldn't come back and train today."

Stewart's comments came just days after veteran defender Tom Lonergan missed Friday night's semi-final against Sydney due to food poisoning and led to speculation that illness might be spreading through the group ahead of the preliminary final.

"I think it's just us two at the moment … bit of quarantine," Stewart said.

Cats officials were understood to be bemused at the comments.

Stewart is nursing a tight hamstring after Friday night's win and would have to pass a test to be available for selection.

He said scans on his hamstring "came back positive" and he expected to be right to play in five days' time.

The Cats face Adelaide in a preliminary final on Friday night at Adelaide Oval.

When they played the Crows in round 18, Cats' defender Harry Taylor presented his Adelaide opponent Josh Jenkins with some ham he had kept in his sock after Jenkins missed the previous game with food poisoning when he ate a dodgy ham sandwich.

The Geelong team is scheduled to travel to Adelaide on Thursday afternoon.