Could be condensation, especially if it’s been very damp and wet where you are then drying out, otherwise the sensor could be failing. If it is then it will get gradually worse & you’ll have to replace it.
I’m not a fan of wd40 on this type of task, if it’s damp then drying out would be a good start. I once borrowed my wife’s hairdryer to do a similar job. Whilst you’re in there check the carpets for dampness to make sure no water is getting in. Also make sure the hood is nice and tight just in case.
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