no
there's no such thing as venial sin
reason for that is because all sin is mortal, demanding a sentence of death for offending The Eternal; as demonstrated by the fact that the Eternal Son had to die for every sin, for there is no remission of sin without the shedding of blood
but as for yawning in public, well depending how bad your halitosis is, or if you have a notoriously grotesque uvula, it could cause distress and revulsion on a par with picking your nose to a fellow human, who being made in the image and likeness of God is therefore 'sacred', and to sin against one is to sin against The One who made them
alternatively if you make big groaning noises while stretching your arms like a boor, you're displaying an almost aggressive disdain for all around you; and that would indicate an attitude of heart that is tantamount to idolatry, since you value your freedom to express weariness of more worth than the peace of your fellow man, thus making a god of yourself
sorry i can't think of any other examples where one's yawning could be symptomatic of sin, though i'm sure if you gave me an hour i could come up with a couple more
that being said, y'know what's really offensive?
this guy at >>738713 not saging your slide-thread