Sent off an unconsidered 40-1 chance, despite winning all three of his previous runs over fences, Adam Wedge's mount just fell short to Paul Nicholls' runner in his first attempt in Grade One company.
Laura Morgan's burgeoning and in-form Leicestershire operation did gain a measure of compensation with Big Changes winning a Doncaster handicap chase on Friday, followed by Whistleinthedark downing the Nicholls-trained Cap Du Mathan at Kempton on Saturday.
"It was a great week," said Morgan. "Notlongtillmay well deserved to be there after what he'd gone and done.
"I suppose some people will think 'smaller trainer', and he has won around tracks like Musselburgh and Wetherby, so there was a question mark about going there in their minds.
"But he ran a screamer, especially off level weights, so we are delighted with him."
Notlongtillmay, owned by former Nottingham Forest and Leicester City defender Alan Rogers, could head to the Manifesto Novices' Chase, the opening race at Aintree's Grand National Festival.
However, the promising seven-year-old may instead be held back for the Jordan Electrics Ltd Future Champion Novices' Chase at Ayr on April 22.
Morgan added: "He seems to have come out of it really well. I'm really pleased with him. He's squealing and bucking in the field. He'll have an easy week of it this week and then back to it again next.
"Aintree or Ayr will be the plan. One or the other. It depends. He'll tell me, I think. We won't rush anything. If I don't think he is on the form he was going into Cheltenham, then he won't go to Aintree.
"We will just give him an extra week for Ayr and he will tell us."
Nicholls was one of the first to congratulate Morgan following Whistleinthedark's success under 3lb claimer Patrick Cowley.
"We got our revenge on Saturday," added Morgan. "Paul came up to me and said, 'Ah well, you beat us today!'.
"I thought, 'I'd sooner have beaten you on Thursday!', but it was brilliant."
Whistleinthedark has won all three of his starts over fences and the eight-year-old could have his sights set a little higher now.
"He looks very progressive and very exciting," said Morgan. "He will either go to Aintree or maybe Ayr.
"It is nice to have a few to be going to these bigger meetings with. It's nice to give the big boys a bloody nose once in while, otherwise it gets boring!"