I wonder whether you're confusing regular XP with the extra XP we got during the pet week recently? I think that may well have been 1 to 17 in one tamer battle, but it was the result of a special buff for that event only. The next pet event starts on Dec 30th.
From the formula at viewtopic.php?f=10&t=8829
I would expect
15.0*[ (your_pet_level + 9)*(30 - your_pet_level) ]
= 15 * 10 * 29
= 4350 XP
for a level 1 pet at Ashlei, without hat or treat.
I just brought a level 1 to Ashlei, no hat, no treat, and got exactly that:
I ended up at level 11. 4350 is enough XP for level 11 but not enough for level 12 according to the table here: viewtopic.php?p=107583#p107583
so that is consistent.
No, I don't think there have been any recent changes.