DH hurt his back!

We were at the zoo all day Sunday and had a blast! But my poor DH hurt his back giving DS piggyback rides and then working the next day (he works freight at night) I feel like a horrible wife though because I got antsy today and told him "my fertile window is in 4 days I hope your back is better" omg who says that?! I felt more worried about getting a BFP this cycle over whether he felt up to dtd, all I can think to do is cook him a nice dinner tomorrow and apologize for being insensitive. Does that sound like a good idea? Am I overreacting?