"Some nutcase must have taken out money, seen the transaction didn't appear on screen and assumed he hadn't been charged," local IT engineer José Luis Ávila told The Local.
Rumours spread like wildfire on social networks and soon queues of opportunistic islanders crowded outside CajaCanarias cashpoints in a money-hungry frenzy.
But what seemed to be Spanish banks' biggest act of involuntary generosity in recent times turned into a grim reality when account holders saw their money had actually disappeared the next day.
The mix-up was triggered by news of the merger of local bank CajaCanarias with Caixabank, which had previously announced that withdrawals would not show up during the switchover between IT systems.
"CajaCanarias sent out letters, emails and posted messages on their websites to let customers know beforehand", said Ávila, who is a Caixabank account holder but knew about the glitch in the system.
"They warned that between 10pm and 3am on Friday night cashpoints would not show withdrawals on cash machine screens. First they transferred the accounts, then the transactions.
"I've worked in these kind of systems transfers before and they're by no means an IT glitch; it's just a process that takes some time to get all the data in order."