I've been friends with this guy since age 13. I'm now 18. He's always been short of money, as his family is not wealthy. I've often paid for things for him without minding too much, though it does get frustrating when I have to fund our hangouts.

Recently I invited him to a concert which my gf wanted to attend. It was £13 (not hugely expensive) and, since he said he couldn't afford it, she offered to pay for him. 

Later, I wanted to buy some drugs and, since I didn't want that much, asked him if he wanted to go splits with me. I don't need £20's worth and so asked him to put in £10 so we can just divvy it up. He immediately said yes, despite the fact that that is almost exactly the same amount as the concert. It is also worth mentioning that he has a part time job and recently spent £140 on a pair of headphones.

I only later made the connection that this was a bit hypocritical. AITA for thinking that he's tight for this contradiction?