Did anybody else notice the stickers were left on the tire treads when LdG left the garage? At the very least, a sloppy mistake - get a sticker lodged in front of a radiator or sucked into the intake, and you've got problems. Nevermind on the offchance if one got stuck across a driver's visor.
But if the production stickers were still on the tires, that suggests to me the tires were being run as-is, right out of the molds - release agent still on the surface, too. IF that were the case, and I'll say it unlikely, running their test car in the rain like that really makes me question the company's attention to detail and quality of testing methodologies.
Think about the veritable tire lottery we've had this season. How 'bout Schumacher's bad set of Pirelli's at Silverstone two weeks ago. The razor-thin operating window of the tires all season so far. The unpredictable performance drops, and (I haven't crunched the numbers, just going by memory) the larger than normal disparity between teammates at any given race this season.
If there's substance to all these, or even most of them, I'd see good reason to start scrutinizing the quality of the tires lot more closely. Hell, even some spot tests of rubber durometer using ND methods could even spotlight inconsistency.
Not trying to fuel a witch hunt here, just asking questions about some odd happenings being observed...