Miller finished fifth at MotorLand Aragon, having run third until he ran wide at Turn 16/Turn 17 on Lap 11 and let both Aleix Espargaro and Joan Mir through.
He wrote in his post-round newsletter of “some issues with my leg that were a bit weird with the lever as I was trying to shift gear,” although other comments from #43 suggested a technical problem.
However, Pramac Racing's Martin also had an issue with his left leg on his way to ninth at the chequered flag and, like Miller, rides a GP21-model Desmosedici.
Remarks from the Spanish rookie this weekend at Misano point to the possibility that both were hamstrung by an ergonomic issue, rather than a technical drama per se.
“I'm struggling with one muscle in the leg,” said Martin after qualifying fourth for the San Marino Grand Prix.
“I don't know, it's the muscle which you take out the gears, so in the race tracks where there's a lot of hard braking that you have to take out the gears, I'm struggling.
“We change the position of the gearbox lever and now it's much better, so I think for tomorrow [race day at Misano] it won't be a problem.
“I will work here today in the Clinica [Mobile, MotoGP's medical unit] and let's see if we can improve it for tomorrow, but anyway I think it won't be an issue for tomorrow.”
Queried further about how the ‘injury' came about, Martin implied that the problem with his Desmosedici was somewhat circuit-specific.
“I don't know; in Aragon [Round 13] I struggled because in Silverstone [Round 12] we changed the position, and we forgot to change for Aragon, so it was maybe too much upper than in Austria [Rounds 10 and 11], so that's why I have this issue,” he responded.
“But, I think now it's back to normal and I am improving every session.”
Miller, who is again set to start from second on the grid tonight (AEST), was asked in the post-qualifying press conference about the problem which he experienced at Aragon.
While his answer was somewhat vague, it was at least consistent with Martin's explanation.
“I think it was more of a specific problem on that day, and it shouldn't be an issue here,” said the Queenslander.
Miller's team boss, Davide Tardozzi, was questioned about the matter on the television world feed during Friday practice at Misano.
He confirmed that Martin had also experienced a problem with his left leg, but suggested it was exacerbated by a previous injury, presumably one sustained in the crash at Portimao which cost #89 four races.
“I think that Jack can fight for the third place, but he had a small problem on the left leg and he couldn't ride in the proper way,” admitted Tardozzi.
“We are pretty sure that he recover this problem, so here in Misano it will be a hundred percent.”
Pressed then on the possibility that another rider had the same problem, Tardozzi added, “The other rider is Jorge Martin, but he suffer a very, very bad injury.
“In this respect, Aragon, where there is lots of effort, mainly after the [Reverse] Corkscrew, going down for the left leg, it's a problem, so there if you are borderline with your body or your leg, the problem comes out.”
Test rider Michele Pirro, competing as a wildcard this weekend, ended up 14th on the grid for tonight's race, which is set to start at 22:00 AEST.