My wife has been tracking flight prices for Melbourne to Dublin on Etihad after xmas, checking daily to find when they released their best deals. We need 2 adults and 3 kids, so it's expensive and normally anything under $7,500 is good.
Yesterday we saw flights for $7,800 on her tablet and decided we couldn't wait longer, so went upstairs to book them on the computer. On the computer (same network, same DNS) the same flights were $7,400. Checking on my tablet (Chrome, Android, same as hers) I also got the $7,400 price. When she searched again on her tablet and she still got $7,800.
Checking today she is now getting the $7,400 price on her tablet as well.
So if you're going to buy direct from Etihad check the same flights on another device first!
It could be down to the different subclasses and availability within those. If someone doesn't complete their booking, those seats are freed up again.