Adding an acknowledgment essentially doesn't cost anything, so there's little reason why the authors wouldn't want to do it if you helped; however it is true that there is still some awkwardness involved in asking others to credit you.
One way to defuse the awkwardness could be to focus on tangible practical reasons why you think this acknowledgment could be useful to you, instead of more sensitive subjective reasons (e.g., I want to be acknowledged, I feel like I deserve the acknowledgment, etc.) E.g.,
In case my bug fixes were useful to you, do you think you could point it out in the acknowledgements section? This could be helpful later to show to [thesis committee / potential future advisor / supervisor / etc.] that I made some contribution to the paper.
Essentially the idea is to sidestep the embarrassment in "admitting that you noticed", or embarrassment on their part for not having thought about it themselves, having possibly hurt your feelings, etc.; and just frame the request as something motivated by a practical need. (Of course the need may be completely hypothetical -- it's just an excuse to avoid mentioning more subjective motivations.)