That's a weird one, I think you're close with the fast animation and have a feeling this is due to the number's lerp being cut off early and not making up the diff. Not noticeable when you only lose 1 frame from a few seconds but very noticeable when it only runs for 2 or fewer frames. It's just a guess from some other issues Ive seen and hopefully should be fixed in the next update. It'll be something to add to the testing as least.