Sickness, perhaps? Mechanical problems? Or just a bad day with the legs? Regardless, it was exactly what Bennett wouldn't have been hoping for on the toughest mountaintop finish to date, with the final 2.55 kilometres of the La Camperona providing a punishing average gradient of 15.14 per cent, including a just-get-off-and-walk stretch of 24 per cent.
Only the strongest would survive, and while Oscar Rodriguez took the victory from a gigantic breakaway, it was Nairo Quintana who was the best of the favourites, crossing in 21st, six seconds ahead of Simon Yates.
The rest of the big contenders came in within the next 20 seconds, including Miguel Angel Lopez, who overcame coming to a standstill after an incident, while a bunch of pseudo-GC riders such as Tony Gallopin and Ion Izagirre also surprisingly finished nearly a minute ahead of Bennett, who heaved across the line, just in front of race leader Herrada.
Herrada clung on to the leader's red jersey, holding a 1.42 advantage over Yates, with Quintana looming a further eight seconds back. However, the climbing continues over the weekend, with Herrada surely set to lose the lead in the mountains as the contenders strive for glory.
After this morning, Bennett won't be among them.
* In the Tour of Britain, the Kiwi duo of Patrick Bevin and Dion Smith continued their excellent form, with both riding strongly to take top 10 finishes on stage six.
Bevin finished in fifth, 21 seconds down on stage winner Wout Poels, to remain in fourth overall, while Smith came home in eighth place at the same time to make a jump on GC.
Both were impressive results on a punchy 3.2 kilometre final climb, which saw the pace set high from the start as Bob Jungels tried to set up teammate Julian Alaphilippe for the stage victory and possession of the leader's jersey.
One out of two ain't bad, with Alaphilippe's attacks being matched by Wout Poels who jumped away late to win the stage and move into second overall, 17 seconds behind new race leader Alaphilippe.
Surprisingly, former leader Primoz Roglic cracked, paying for his effort to catch Alaphilippe and falling off the pace with 1.3 kilometres to go and dropping to third overall, 32 seconds behind Alaphilippe and just 14 seconds ahead of Bevin.
The Kiwi pair were two of the riders to pass Roglic on the way up the climb, with Bevin claiming his fourth top-five finish of the Tour and retaining his points jersey, while the 25-year-old Smith again showed why he's one of New Zealand's most promising riders, with a breakthrough result surely not too far away.
He'll have two more chances in Britain, with the final two stages favourable to both Smith and Bevin as they continue to grow New Zealand cycling's presence at the top end of major stage races.
Not enough cycling babble for you? Tune into Radio Sport today at roughly 11.20am to hear a sleep deprived Niall Anderson talk about all of the above with rapid Six60 fan Elliott Smith.