Timing belt tensioner 1.6 BSE

Hi I have a 2011 estate 1.6 BSE 75Kw engine

I have just changed the timing belt, and everything is running fine, and drives well, I've drove just over 80 miles since fitting it,

I've took the cover off today to check the tension was still fine, but it is slightly off set.

I loosened it up and re-tensioned it with the markings lined up, and torqued the nut to 23nm, I turned the crankshaft twice and it went back to being slightly offset.

Is this a common thing on this engine or could it be a faulty tensioner, I've not seen it do this before on my old car. 

Would this cause an issue as it's only a bit offset, or should I contact SKF for a replacement tensioner, id be happy to strip it down and replace it to be safe, but if it's normal then I could leave it. 

Any help would be appreciated as it's puzzled me

Thanks