Does this warrant authorship?

Based on what you described, in my opinion that would not be enough for authorship unless your contribution involved some kind of data manipulation that was more than cosmetic. At the same time I would never ask someone who was not involved with the project to make a figure. That said, I know that in some cases authorship has been given for less than what you have done, just like I know cases where people have done a lot more than you and still did not end up getting authorship.

I hope your colleague told you beforehand that your figure(s) may end up in a paper, or at least that the paper was not submitted without your approval to use the figure(s). You certainly have a right to ask for acknowledgement or authorship, and not give consent to use the figure if you get neither. I think in this case at the minimum you should expect acknowledgement and I would give it to you, but people are different. Finally, you can ask to be paid for your effort, in which case the monetary reward would take place of acknowledgement/authorship.