I suggest you think of your father not as your father, but as a person to be - well, I was going to say manipulated, but what I think I really mean is MANAGED.
It benefits you for him to do this for you. It's definitely weird that he showed you the bill. But if you would like to benefit from his largesse in the future, simply respond "gee, thank you for the generous gift. " Don't get sucked into any more discussion than that. He may have been looking for credit for his generosity or he may have been hoping you'd pay for part but just ignore that and say thank you.
Same with other things. Keep your expectations at zero. Don't get sucked in to any changes of mind on his part. Treat him as you might a crazy aunt who you would like to keep receiving financial help from but have to MANAGE.
Or simply decline offers of help in the future but I know that financially his aid has been useful to you sometimes.
And just remember this is not normal dad behavior. Who knows what drives it - guilt, narcissism, wanting to keep you by keeping you beholden to him - who knows? But just accept that he's not who you wish him to be but on some level he is trying to be helpful and just manage that.
