Why does my dr. pepper taste like soap and why did it make my mouth go numb?

i was rather puzzled today so i asked the generous Yahoo!Answers community.

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okay, so i usually drink dr. pepper. in restaurants, at work, at school, everywhere! actually, i drink wayyyy more soda than i aught to be. i work at a gas station where i can drink fountain drinks for free. i drink about 16 ounces of dr. pepper for every hour and a half during my 8 hour shift and than more depending on where im at or what im doing outside of work. so, yes, i drink A LOT of dr. pepper and i love how it tastes.

today at school, i got a can of dr. pepper from a vending machine to sip on while digitizing some raw video. i get in front of the computer, crack it open, and take a swig. it tastes kinda funny. i try it again to double take the sensation, my tongue notices the inside of the rim as i drink it, making sure my tongue gets as much flavor as this soda has to offer. it kinda tastes like dish soap. its not really a bad taste because its still sugary but the taste of soap is odd. the carbonation level is at a normal and its still pretty cold.
as i continue working on the computer and pondering this soapy taste, i start to notice my mouth feeling weird, like i put oragel on my lips, teeth, and tongue. now i know the acid level of dr. pepper is high but like i said before, i drink it a lot and my tongue has never gone numb.
so, its been about an hour and a half since the first sip and about 30 minutes since my last. my tongue is still kinda numb feeling and i still have a soapy aftertaste. i didnt pour it out because im waiting for a family member to come home and see if its just me or if this soda has got some funk to it.
if any of you has an idea of why this soda is treating my mouth the way it has, please help me with some explanation or just tell me im a crazy idiot and it was a waste of time and 5 points asking this question.

thanks

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R.E.s answer
There was likely something spilled on the outside of the can. There is little to no chance of knowing what it was at this point.
Solution- Always rinse cans (this includes pantry cans) before opening them! They are known for having all sorts of terrible things on them. I will spare you the details as to common substances found on cans. I promise you don't want to know. Anyway, you didn't die yet, so you are probably fine.

(jesus! you recieve the best answer! i will for sure wipe off my cans from now on.)

zanys answer
Okay i don't know why it tastes like soap
but it makes your mouth go numb cuz its fizzy!
-zany

(fuckin, duh, why do ya gotta go and get all smart on me like that. i cant believe i let that pass over my head)