hey nikki, could it be related ot his recent cold? Ethan has an occasion dry cough since his cold & no other symptoms..
but if asthma is in the family it could be that or hayfever as your dh suffers from it.. those were the 2 things I was going to suggest.. if he doesn't seem unhappy or sick & it's not slowing him down like you say then I would see how he goes over the weekend..
but not telling you what to do - it's your choice as you're his mummy
keep us posted how he's going