It was a little bit too much too soon, but Andy was beginning to see that Woody was just a really open and forthright kind of guy. It was a kind of antithesis to his own character but it wasn't a bad thing at all. He nodded, even though he knew he wouldn't bother Woody with any of his issues; he wasn't thinking about the nightmares he might have and the disturbed sleep Woody might end up having because of him.
Called out, Andy ducked his head down in embarassment, mostly because he knew that a laugh wouldn't have been such a surprise from anyone normal. He'd been called morose at best and sulky or miserable at worst by people before, but it was his defensive and cautious nature - a result of necessity rather than natural inclination - that made him less inclined to humour.
"I don't think I'll be doing that." he assured, still looking away.