The fact that the text appears correctly when you zoom in seems to indicate that this is related to the relatively low dot pitch (optical resolution) of computer monitors. Keep in mind that printing at below 300 dpi (dots per inch) is considered low resolution, but a computer monitor might at best sport around 100 dpi. For example, the monitor I'm sitting in front of typing this packs 1920 pixels into 52 cm visible display width, for a resolution of 1920 [dots] / (52 [cm] / 2.54 [cm/inch]) = 93.8 [dots/inch]. (1 inch equals 2.54 cm.) If it were 300 dpi, those same 1920 pixels would cover about 16 cm physical length.
Because of the low dot pitch, if it happens to be in just the right place, character spacing (kerning), font weight, and a number of other aspects of typesetting don't always show quite correctly on a computer monitor. Displaying in higher resolution, such as in printing or for that matter simulated by zooming in, gives more accurate results because the computer has more individual pixels to work with.
If it looks right when you zoom in, and layout on screen isn't critical, I would say don't worry about it. If layout on the screen is critical, you may want to try different fonts to see if some other one doesn't show the issue so clearly, but you cannot guarantee to completely eliminate the effect.