not that i'd advise against reaching out to the client, and communicating your feelings as you did to us.
i admit if a provider did that to me i would be touched.
however, in my opinion you should offer a little extra incentive to make him want to see you again, esp if this was a first date. not saying you need to discount your price, though that's an obvious option, esp. since most providers i have seen on these boards are not against running a special every now and then. you could look at it as a one time special for a specific client. and i would also make sure the guy knows that if you give him a discount it would be for this one time only and only to help make up for the less than stellar service he got the other time (so don't go around bragging that he got a discount from you).
but another option, and one i would recommend over a price discount, is maybe throw in some extra time...another half hour to his paid hour perhaps.
especially if this was a first date. if it were me and a first date was terrible, even if the lady communicated with me that she felt she was off her game, i would be hard pressed to find it within my self to pay her asking price again on a promise that things would be "better." if she were a total stranger to me, my thinking would be "well that promise of better service was implicit in the first go around, what makes me think she would be any better this time? her word, the word of a complete stranger?"
however if you offered me a discount or extra time, i'm scottish enough to take advantage of a deal and would probably give you another chance. but then again i don't have a huge amount of discretionary income, so my provider dollars have to be spent wisely.
on the other hand, if this was a client you have seen before and obviously have chemistry with, i think a communication alone would probably set things right.
again, i know i'm a minority with this advice, so do with it what you will. i do agree that communicating your feelings would be a good step in the right direction.