Well that's it then
Nothing wrong with that. You'll get better noise reduction and hot pixel removal by offsetting anyway. You just want to make sure your alignment or balance is not too dodgy as to loose the galaxy between exposures though
. The slight elongation of the stars in the same direction as your drift is probably the guider not coping during the exposure with the same thing that causes your mount to shift the whole frame from subs to subs. Definitly not flexure. More like balance. Flexure is "sneaky" it creeps on you...