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Did you allow your scope to cool? A warm mirror or poor seeing shouldn't show ghosting though, but rather a blurry, 'boiling" image at focus.
If you're getting ghosting, it could be the eyepiece (those cheap 2" GSO EPs are not the best at F/5 and certainly can introduce abberrations to the view). However, you mention that the view with the same eyepiece improved after a bit of time, I suspect that you did not allow the mirror to cool.
You also mention that your laser collimation was off by up to 4mm. That will matter at F/5. You should also note that the collimater itself might be out of adjustment. It's easy to check for this, put the collimator in a V-block, aim it at a wall a few metres away and rotate it, if the dot makes a circle motion then your collimator is out of alignment.
It's better to use a cheshire eyepiece. You can align the secondary quite accurately using the outline of the bottom of the cheshire tube, then align the primary by centering the centre spot donut on the black cheshire dot.
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