There isn't any real way to prove it. But yeah that just happened regardless.
I had 2 tips in my account. The user I was tipping had 1 tip. I might have had a bit of a connection problem I suppose.
So I click "tip user" and nothing happens. I spammed it for like 3 times in a row and now I don't have any tips on my account and the user I tipped has 3.
Not the biggest problem in the site I suppose.