Don't over-think it. There's actually over 1/2" of play at plates when you loosen axle. Just happens that they were at roughly correct placement, so you won't notice play unless you yank on them. What you can do is shove wheel forwards to take out all play from adjusters, then use bigger nuts on each side to pull wheel back and take out chain slack. This keeps both adjusters under tension and no play!
Also lookup "string method" for aligning wheels. Due to manufacturing tolerances and wear & tear, markings on swing-arm may not accurately reflect physical alignment of wheels. Using string to line up all 8 edges of tyres ensures proper alignment. Then you may want to make new marks on adjusters to show true alignment.
Good job, it'll be easier next time!
Link to original page on YouTube.