Why shouldn't it be - we get distracted when reading all the time. It's valid as reading. Nevertheless, if you find yourself getting distracted all the time, it is better to put the Qu'ran down until your mind is less distracted by whatever is going on around you.
However, in prayer, when we recite surahs it is not valid as prayer, as the focus should be on the prayer, that is to be mindful of Allah.
In such a situation I would suggest that you start again; unless it is jummah prayer, in which case, I'd advise you to do better next time.
I'd also query why are you reading the Qu'ran in a place where 'rodents' are about. It's better to read in a clean and healthy environment. If it is in an educational establishment attached to a mosque, or otherwise; then I'd take this up with whoever is in charge of it.
I'm replying to commentators here as I'm not able to reply to comments on my phone for some reason.
@Medi-Saif: It's not an opinion to use your own eyes and mind when you've been brought up in an Islamic tradition. Or are you suggesting otherwise?
@Medi-Saif: Which is no different to what I was writing ... So what exactly are your real concerns here?
@Crimson: I'm not addressing anyone with OCD. A person suffering from such should seek medical advice.