Just built myself a fitting for a travel gauge I had to level the bed. The levelling part is easy enough now... But, I'm noticing that the bed seems to rise away from the corners, by about 0.1mm in Y, with the highest point in the centre of the bed. "Seems" is the operative word, I think - I'm pretty sure the glass isn't warped (this is cold). I can get a further contribution of about 0.04mm by moving the carriage about, so I'm pretty sure this is the X/Y axes flexing. Is this a normal amount? Has anyone else measured (or noticed) this? If it's not normal, what do I need to look at?