It's never happend to me, but I wouldn't worry about it much if it did. Even if someone feels inconvenienced by your headlights it will only be for a fraction of a moment. As long as your headlights and bulbs are both DOT compliant there are no worries, people are simply annoyed that your headlights are so much brighter than yours.
I'd imagine your headlamps themselves are the same USDM spec that came with the vehicle, right? Headlight lenses/reflectors are designed to direct the light output towards the shoulder away from oncoming traffic. I don't know how it works for Rovers, but RHD Specification vehicles do the same, but it's ineffective if used where traffic uses the right side (LHD Vehicles). I have this problem on my S13 as I have Hella Euro-Spec H4 Conversion Headlamps.
It could be that the previous owner, if there was a previous owner, swapped out the headlights for some European Specs. Again, I don't know how this applies to rovers, but a lot of times foreign market headlights will lack bulb covers that limit the amount of light put on the road, lens made of glass instead of plastic, clear lens instead of crosshatched, or lack amber reflectors.