Am I being paranoid ?

Posting annonymously - 
Am I being paranoid or would you suspect something ...
We both activated find my friends so we new when to get tea on etc etc 
My partner works in a welding warehouse and has done for the past 3years - everyday without fail he comes home FILTHY and smelling of burning metal and dusty - his hands face and arms are normally black with oil and dust - his clothes are normally filthy too!! 
Anyway - yesterday and today up to 2:30 he disabled find my friends .. And today he's come home without one mark on him, he's spotless, not one black mark on him and smells as clean as a man does not working.. He's also been really short on texts throughout the day ... I've asked him if he's been at work he's got all defensive and wouldn't even look me in the eye?!? 
He couldn't be on a different job because they are short on welders down to 7 from 20!! So I know he hasn't been on a different job 
I mean does this sound dodgy or am I overthinking things ... Please someone 😩
Forgot to add : I asked him and he wouldn't even look me in the eye but said 'yes I've been at work' stormed off upstairs and fell out with me .. I didn't say I was being paranoid he called me paranoid that's why I asked if I'm being paranoid