I've had this also...I've even had it in my online bank, I logged on as usual but there was a page asking for my password,pin & the 3 digit code on the back of the card
my husband called the bank & it was not them...I hear there is A LOT of this going on where scammers will insert a page in a legitimate site to ask for & intercept your info...we where told that NO ONE from a legit site will ever ask for this info, NEVER give it out...they said to always call the place & ask first
You where lucky you weren't able to provide this info..