Me (25F) and the guy (28M) who I'm dating for 3 months flew all the way from US to Europe to surprise me. Is he too fast?

I'm from Austria and I'm dating a guy from US for the last 3 months who I met here when he was on a deputation. He left for US by the mid of last month and will be back here in a couple of months. So we make it a point to catch up daily on the phone but so far we haven't spoken about taking our relationship to the next level (i.e.) officially as BF and GF.

This week I had my birthday and he flew all the way just to surprise me and he left the day after. I was really happy on seeing him but somewhere I feel it was too much of a big step at this stage. I do like him but somehow I feel he is more attached to me than I feel about him. How can I let him know without hurting to take things slow?

tl;dr: The guy I'm dating flew to meet me on my birthday and I feel it is too early for such a big surprise.