When I am scrolling answers on my iPad, my taps are sometimes considered as votes. Usually I notice it immediately and undo it, but a couple times I've noticed it too late and my vote was already locked.
The other way to accidentally vote is just to keep iPad (or iPhone) in hand and unintentionally press by left hand thumb on vote arrow.
The site has an easy ability to vote( and it's good) and so hard to undo the vote after 5 min( and it is not good)
With an increased number of touch devices (e.g. iPad, iPhone and other smartphones/tablets), it's one more reason to remove the time lock for votes - see related What is the justification for locking votes? and Vote too old to be changed, unless post is edited