The seller can report you for an invalid retraction, since there is not a reason to retract according to ebays retracting guidelines. Ebay could suspend your account for atleast 30 days.
if the seller reports you, you will get slapped by ebay. Most sellers don't know it's a reportable offense.I retracted a bid, when I was a newbie (I accidently entered the wrong amount, if I remember correctly) and nothing happened to me.
I think if you did it repeatedly, it would probably be a different story, though.