No, It's called bad habit. Not all guys do this. I know it's off putting but is this small thing a deal breaker if you have everything else in common? You have to decide that. If not , try speaking to him about it. it shows no public manners picking your nose in public all of the time.
I heard one of the biggest signs a relationship was getting serious is when a couple started to fart infront of each other, maybe this is just a different version of that. But no its not that common to do infront of others, but some do no doubt.