As a customer am I leagally liable for an employees mistake?

So here's what happened. I pull into the gas station this morning. I'm in california and there is no such thing as pump and pay here, everywhere you go you have to pay upfront for the gas. So I go in and I hand the clerk $3.50 in change and say 3.50 on 7, walk out, go to the pump, start pumping the gas and zone out till it stops. I wasn't paying attention at all because when you give them cash the pump automaticaly stops when whatever ammount of money you gave them is used up. Plus it's first thing in the morning, havn't had cofee yet, etc. etc., so I'm not exactly at my most allert, and different stations pump slower or faster so the ammount of time didn't really don on me either...and besides in 10 years or driving and getting gas I've never seen this happen so I'm not exactly of the opinion that you need to pay that much attention when pumping gas, or at least I wasn't untill this happened...So anyway, the pump stops, I go to put it back on the hanger and as I'm screwing my gas cap back on and this guy comes out yelling at me saying "Hey you have to pay for that!" I'm like what???? he points to the pump so I look at the pump thinking what the heck is this guy talking about and it says it pumped $29.96 worth of gas... 0_o So I'm thinkin crap! How the Heck is that even possible??? Then it donned on me, it couldn't have pumped that much unless the clerk entered in the wrong ammount because I only gave him $3.50. So I tell the guy look I don't think I should be held responcible for this because it was your employee's error not mine, It's not like I intended to steal gasoline, quite frankly I didn't even know it was possible to do that. So anyway I'm trying to reason with this guy and tell him look I don't have any other money why do you think I gave you only $3.50 in dimes and nickles? I broke thats why! He tried to tell me it was my fault and I was responcible for it so I asked him how the heck I could make the pump keep going like that if I only gave him $3.50 and the guy then addmitted that HIS employee entered the wrong ammount into the computer. I told him I'm not responcible for the error your clerk made, if you'd like to siphon it out your more than welcome to but other than that I don't know what to tell ya because i don't have any more money and he proceeds to threaten to call the cops on me and writes down my licence plate number! I asked him what the heck he wanted me to do I don't have any other money, and he tells me I have to come in tomorow and pay for it or he'll file a police report for stealing the gas!!! Realistically I'm gonna go back and give the guy the money when I get paid tomorrow cuz it's not worth the hassle to me to get police involved but I am curious... can I really be charged with stealing for something that is 100% not my fault like this? I just don't see how some one can hold me responcible like that for something their employee did??? any advice?