My heart is jumping weard while Im riding is this bad?

I gained about 35lb in a year....And started cycling to loose it...Im really out of shape now Im 190lb and Im 27 y.o. ...Never had any heart problem....I really enjoy cycling but sometimes as I start pedaling fast my heart strart jumping weardly...it is not painfull or anythig just feels funny...its like some kind of disrithmia but for a second or two...is it dangerous or it is fine and maybe it will go away if I practise more?