The latest batch I have had is this years cut, whereas the one before was last years, this may be the same with you and explain the difference? I find the hay changes each time but is usually of equal quality and nomminess. I find the Timothy and Rye stays the most 'standard' and the Ings changes the most between batches.
I did notice however that the Timothy and Rye was very different, good, but different this time, and Barney didnt like it as much(I should note here that hes a fussy one). I contacted them and they were very helpful and explained that my previous bags of the T&R had come from a different farm, and that it would be available in December again and that they could send me the bags from that farm specifically if I wanted. I love that they knew exactly which farm my hay comes from! So it may be worth contacting them, their customer service is fantastic.