Do you grind your teeth when you hear someone say they were 'sat' or they were 'stood' somewhere? Me too! I always want to ask who sat or stood them there, or did they really mean they were sitting or standing? The increasing tendency to use a passive instead of the past imperfect or a gerund is the result of dialect creep. I have no objection to dialects being used instead of standard English when appropriate, but this construction is not only replacing standard English, it's taking over other dialects as well.
Another example is negative contractions. 'I haven't' and 'it isn't' have virtually disappeared, replaced by 'I've not' and 'it's not'. The latter would have had my schoolfriends and me in fits of giggles when I was little and 'snot' was on a par with 'pooey pants'.
'It's not' just isn't right! Imagine a scene in a panto.
"It's behind you!" the audience shouts.
"Oh, no it's not!" the hero shouts back.
It simply doesn't work. The thing that irritates me about it most is that I catch myself using it. It's not (grrr!) what I want to do at all. In fact, I blow my nose on it! So, to redress the balance, here goes: isn't, isn't, isn't, isn't...