could it maybe be that he meant to say yes, but he wanted to check with the mother to see how much they are able to help you with paying for the wedding? since you had a good relationship with him up to this point, it could be that he assumed that you knew he meant that he supported you, and just was getting down to business more with logistics and planning.
for context: i'm a girl, and got married two years ago. my husband and i both understood that as adults, we were 100% capable of deciding if we were ready for marriage without consulting our parents. however, i do understand that some dads demand such gestures.
if you've pretty much decided between you and your girlfriend that you're going to get married, it's best to keep the lines of communication open with her. if she has reason to expect a ring during the holidays, DO NOT just sit around and wait for her dad to respond for a few months. while it's a shitty situation for you to be in, it also sucks for her to not know what's going on and not be in control of something that affects the rest of her life. i assume you want the actual day of engagement to be somewhat of a surprise, but no engagement should ever be a real surprise, so it's better for you to tell her if her dad is causing the problem. you're partners. if you dont hear from him within a week of asking, i think you should call him and ask him again, but be prepared to tell him the million reasons why his daughter is the most special person in the world.