Stranger still, it was a warning he chose to deliver after the well-travelled striker had produced his best performance of the season on Saturday, hailed by the Burnley manager, Steve Cotterill, as a centre-forward's masterclass.
The 31-year-old forward, rescued from Crystal Palace reserves last summer, hit two goals in the same match for the first time in two and a half years, confirming that the mini-blip that saw United knocked off the top of the Championship is over.
Yet it did not stop Warnock being starkly frank. "Shipps knows the score," he said. "Come the January transfer window, I'll be desperate to sign someone better than him."
Shipperley's goals took him to eight for the season from 21 appearances but Warnock, whose decision to resist the siren calls of Portsmouth, has reinforced United's position as promotion favourites, wants another proven goalscorer. Steve Kabba, ruled out by injury on Saturday, has yet to reach double figures while Danny Webber's return stands at a modest six. The on-loan Vincent Pericard, meanwhile, has been recalled to Fratton Park.
Hence Warnock's feeling that Shipperley's gameness might not be enough, although it did not stop him praising him to the roof on Saturday. "He amazes me the way he carries on," Warnock said. "It was like he had gone back in time the way he played today. When I turn on the television tomorrow I'm half expecting to see the pictures in black and white."
Cotterill wished it had been all a sepia-tinged illusion. "Shipperley was outstanding," the Burnley manager said, "head and shoulders above everyone on the field. It was the best performance by a forward I have seen this season, the way he led the line and took his goals, and he had 10 good team-mates around him, all on their game. That was the difference. We had only three or four."
Shipperley opened the scoring by combining strength and technical prowess, holding off two defenders before unleashing a shot, with minimal backlift, that gave goalkeeper Brian Jensen no chance. Webber applied the final touch to a Craig Short header to double the advantage.
Burnley, who had gone close through Ade Akinbiyi - a potential Warnock target - almost replied when John McGreal's header was stopped on the line, but United were safely in control when Shipperley converted a cross from Chris Armstrong, who was making his first start for two years following a serious knee injury. Armstrong's involvement made Warnock's day complete. "It is such a great story," he said. "He could have walked away with £250,000 in insurance money but he was determined not to give up. It was a gamble to play him and I'm so thrilled it came off."
Goals: Shipperley (29) 1-0; Webber (34) 2-0; Shipperley (81) 3-0.
Sheffield United (4-4-2): Kenny; Kozluk, Bromby, Short, Unsworth; Quinn (Morgan, 85), Montgomery, Armstrong (Tonge, 90), Jagielka; Webber (Ifill, 88), Shipperley. Substitutes not used: Pericard, Barnes.
Burnley (4-5-1): Jensen; Duff (Elliott 79), Lowe, McGreal, Sinclair; Dyer, Hyde, Spicer (Noel-Williams, 59), J O'Connor, G O'Connor (Branch, 59); Akinbiyi. Substitutes not used: Karbassiyoon, Grant (gk).
Referee: C Webster (Tyne & Wear).
Man of the match: Shipperley.
Attendance: 23,118.Reuse content