Mobile phones in petrol stations

Petrol stations are still covered in signs saying "do not use mobile phones", along with the traditional "do not use open flames" and "turn engine off", etc. Should you still do this? On the one hand, I'm pretty sure that the fear of mobile phones is an entirely spurious over-caution, that once someone had suggested it MIGHT be a problem, understandably no-one dared come out and declare that it wasn't, just in case. And that even if it were shown not to be, no-one would go round taking all those signs down, because what would be the benefit? On the other hand, ignoring warning signs because you think you know better is a bad precedent, because it will eventually lead to someone ignoring a sign they THINK they know why it's there, but it's actually there for some good reason.

(After all, if it was discovered this was really a serious risk, they'd probably have to go round replacing the signs with ones that say "No mobile phones. We really mean it. Danger of death"... :))