It would bother me. An ex-BF never bought me anything for either my birthday or Christmas. We were both broke, but somehow I managed to buy him gifts. The weird thing was that I didn't necessarily want anything from him. What annoyed me was that I bought him Christmas and birthday gifts, he didn't buy me anything, and then had the nerve to get angry with me when, after his mother asked me what he had given me, I told her the truth. We broke up very soon after that, after he had: refused to lend me any money for petrol to get to work after my employers had mucked up my pay for the third time, had complained about the amount of money he had spent going out with me, or picking me up from the train station which was 20 minutes from his house, and when I'd spent 2.5 hours and $20 on tickets to get to him, and then he gave me the cash equivalent of the money I'd spent on gifts for him so 'we'd be even'. The last was the single most insulting thing that has ever happened to me.
I guess my position is that this is probably not about gifts, its about other things, which is about the amount of effort bf is putting into the relationship. That, in some cases is measured by money (as shown in my example: apparently I wasn't even worth the amount of money needed to spend time together, and the relationship was defined by cash and obligation - not the way I was working at all!), but in others, as in this instance, it seems to be about time and generosity. To me, the bigger flag is his refusal to pick up the OP's sister when it wasn't out of his way to do so on top of the other things.