Scrod,

I cleaned up my drivetrain the other day, degreaser and reinstall+lube. Today, I noticed the most minute (and I mean almost impossible to catch) play in my pedals. The chain has some slack in it on the top side, but it appears to be a good tension. Do you think drawing my wheel back in the stays just enough to take up that slack will be bad? I've never figured out the "perfect" amount of tension to have slack on the bottom and no play on the top of the chainline.

TL;DR

1. Small play in pedals, isolated it to the chain (around 600 miles)
2. Optimum chain tension that I should be looking for at this point?
3. Am I just running a "broke in" drive train now that is going to have subtle amounts of play as the chain/cog ages?