Just got a little... bored, is all. Laying around like that.
[It reminded him of times growing up when he'd get a little too sick, when his body healed slower, and he'd have to stay in bed for days, sometimes longer. And while Bucky's company (then and now) helped tremendously, it didn't make the fact that he couldn't just be useful in some way any less frustrating.]
[Gives her an apologetic smile.] I'm really fine, though. Sorry for scaring you like that.