Mark Webber and Sebastian Vettel were confused as to why they needed to have their front wings replaced during the Spanish Grand Prix.
Both Red Bull Racing drivers had their races compromised by front wing changes, despite their being no visible sign of damage on either occasion.
The mysterious problem was particularly costly for Webber, with the Australian eventually finishing outside the points in 11th.
Vettel was still able to finish sixth and retain his lead in the championship, albeit now shared with Fernando Alonso.
"I don't know [what the problem was], to be honest," said Vettel. "I didn't think I had any damage on the nose.
"I came on the radio and said it felt like damage or something stuck. We know that there is a lot of rubber on the track and it's likely that maybe a big piece of rubber gets stuck and then it ruins the aerodynamics.
"I wasn't sure and I tried another lap, but it wasn't the right thing to do so we decided to come in and change the nose just to make sure. That cost us quite some time but ultimately it was the right thing because I was told that something on the front left of the wing was actually broken. I don't know why. I didn't hit anybody or anything."
Webber, meanwhile, blamed the delay for leaving him stuck in traffic and unable to fight for a point-paying position.
"I don't know where I got damage on my front wing but I had to pit for a new nose," Webber added.
"I lost a lot of time with that obviously, not only that lap but the two or three before when it started playing up.
"Then when you're out of position round here, you have to do the longest range stop possible and look after your tyres, and then when you catch people, the tyres just get killed. It's chicken and egg. If you push past them, you've got to pit earlier and commit to another stop.
"I was out of position because of whatever happened with the nose. I was stuck behind the Force India and you could see the McLarens doing nothing, Seb was just chipping away doing nothing special. It's amazing. The tables have turned."