I don't think Mrs Fenn was having senior moments. I think this feisty lady would have been less than thrilled by the furore which accompanied the release of her belated confidential police statement - made four months after the event - into the public domain.
Which makes one wonder ... why the delay in interviewing her?
She was a material witness who lived directly above 5A ... but the police asked her nothing. Extraordinary, in my opinion.
Mrs Fenn's son put on record "Gerry McCann did come up to apologise to my mother for all the unwanted attention – which was incredibly kind as he has endured a grief and pain that no parent should ever have to withstand.”
http://www.telegraph.co.uk/news/newstopics/madeleinemccann/8469932/Madeleine-McCann-time-to-forget.html
On 5th May the PJ descended on Luz and did a house to house. Did they visit Mrs Fenn? We don't know so we can't say 'they asked her nothing'.
If they did visit she didn't mention anything to them or she would have been interviewed. There was also a command post in Block 5 where she could have gone and spoken to the police.
The blame for her late statement can't be laid at the PJ's door unless we know a) if they visited her and b) what she said if they did. She also had the option of approaching them if she thought she had relevant information.
We visited 443 homes, some of which were occupied as the inhabitants of those respective homes were questioned whether they had any information relating to the disappearance of the child, Madeleine McCann or if they witnessed another situation and/or suspicious activity during the dates preceding the events;
In the case of an affirmative answer, these witnesses were taken for formal questioning related to the investigation;
http://www.mccannpjfiles.co.uk/PJ/EXTERNAL.htm