It feels touching,  just as seeing anyone say I matter to them would feel touching to me. Knowing that it is part of the ‘set up’ as a therapist, i.e. that if I do my job well my clients may well become ‘attached’ or have positive transference, doesn’t make it any less real a feeling to the client and thus to me when expressed. I would probably assure them that they are important to me too, but in a different way. I often say “ I am invested in you” – which means I am invested in their being OK in their lives and doing well, which is true. That seems to make things feel a bit more congruent, although they are not even at all. That’s why the therapist never takes advantage of the clients feelings towards them.