With the Eels still training under Trent Elkin, Mannah said he had not noticed a change in Hayne's attitude to the club in the wake of Stuart's abrupt departure.
"He's been at training - he's been turning up every day with the same attitude," Mannah said. "There's no point me getting too worried about something that's just rumour."
Stuart quit the club last week just one year into a three-year deal, and promptly announced he had joined Canberra on a three-year deal.
It continues a sorry tale of woe for coaches at the Eels, with Hayne himself having had six coaches in his seven years in the top grade.
Mannah admitted the constant changes at the top had taken their toll.
"It's a tough situation in terms of the instability we've had over our careers," Mannah said.
"We're both the same age Jarryd and I, we've gone through a fair few coaches in our time at Parra.
"Every coach wants to come in and build their own culture and start from scratch."
- AAP