I'm a paranoid person.  The type that jiggles every slot I put my cards into because I'm wary of skimmers.  That precaution isn't enough anymore.

Many television news magazines have run the stories.  You've seen them.  How the nefarious in this world have access to gadgets that skim your credit card number when you make a legitimate purchase.  These skimmers can be easily placed over a slot and steal your info.

Thieves in Palo Alto have been found placing skimmers inside gas pumps.  They got access to the circuit board inside and made off with over 3,600 credit card numbers.

Be aware and be careful.

For more see this source article.