This is just one of those things that, despite your best efforts and intentions, is ultimately out of your hands - different buyers like different things and there's no way for you to know which ones prefer what unless you ask each and every one; and you'd probably get worse stars for communication if you did that.
Case in point, I have read many experienced buyers on the board say they don't want the automated emails let alone direct communication from the seller (unless absolutely necessary). One could read that and decide to no longer send messages. On the other hand, I've read very experienced buyers/sellers complaining that when they use a high FB ID, they get no direct communication, but if they use a low FB ID to buy, they do get communication - no one seems to think it's the seller attempting courtesy according to the individual buyer and situation, based on the general consensus of more experienced eBayers...
Like you, I am a smaller seller, and unless a parcel is going to be marked as posted within an hour or two of purchase and payment, I send a direct message to every single buyer, regardless of FB score. I do it because it's how I want to conduct my business, and because there are many who appreciate it, and for those that don't, I rely on them at least being able to recognise it is done out of respect and not an attempt to annoy. I'd rather annoy one every so often for "over-communication" than annoy a few with no communication. 😉
Also, it just may be that the star was left in error - there's an unfortunate glitch with the eBay app(s) on smart phones etc that make leaving feedback, DSR etc more difficult and errors like unintentional low DSRs and negatives are know to occur because of it.
