I typically put several items into a shopping cart on Amazon and then do one large order. This works for me.

Interesting - Today I added another item, and the Amazon 'price increase warning page' came up noting over $15 in price increases across 8 items that I had in my cart. One CD went up $4 alone!

Is this the sign of something to come/something going on at Amazon, or am I way behind in noticing this trend?

I've seen the same thing over the past month or so. I keeps hundreds of items in my "save for later" section to watch for good used deals. Amazon is undergoing daily price increases - seems pretty substantial as well.

I expect you can look to Amazon's recent stock trouble for the reason - I think it wasn't long after Prime was introduced that it started. Maybe they wanted to lock in repeat customers and then raise prices. Disappointing perhaps, but I really just used the used features anyway... I will remain a dedicated customer.

Same here. I stopped buying from Amazon as much because it seemed like prices were much higher. Now I get the "important messages" screen saying prices have changed for items in my cart.

Here are the changes in my cart:
$8.25 raised to $11.00 (+33%)
$16.49 raised to $24.99 (+52%)
$16.95 lowered to $11.53 (-32%)
$16.32 raised to $24.00 (+47%)
$18.95 raised to $22.95 (+21%)
$10.50 raised to $12.92 (+23%)

This is a weighted increase of +23%, a very dramatic increase.

I for one won't be buying much from Amazon at these prices. There's no longer a large enough price difference compared to my brick-and-mortar Barnes and Noble.