Well too tight is interesting. The grinding or what you thought was grinding may have been just the motor noise which has kind of a rattly pitch to it when doing regen, at least on my Ribelle it does. At slow speeds you can actually feel it bump bump between poles as you are walking the bike if you pay attention. HOPEFULLY it was that and not bearing damage due to the chain being super tight!
How would it get that tight though? Did you adjust it at some time in the past or did you get it like that, because generally they loosen over time no? Even then, after 3k miles, Id think it'd would loosen itself up a bit anyways if it was super tight.
correct me if I am wrong but Id think overall, if you miss the mark on tension, a bit on the loose side is better than being too tight as it does not bear on the bearings so hard, not to mention the bike does ride a lot quieter with the chain a bit loose. This caught me off guard the first time I adjusted my chain, I took it for a ride and could really hear the chain / gear noise then, enough that I turned around after about a block and re checked everything. The chain was actually a bit warm which concerned me and after measuring, seen that the wheel apparently slid a tad when i was tightening the axle nut and it was much tighter that I originally set it to, so I basically undid what I adjusted and it was quiet again.
As a side note, make sure you have the wheel aligned too when you tighten up after a chain adjustment, as it's fairly easy to cock it a tad and you can easily tell by looking at the dirt mark on the tire if it's off center from the center of the tire.
Im glad you got it sorted out and it was nothing major.
Aaron